1
|
Mukherjee MM, Xu P, Stevens ED, Kováč P. Towards the Complete Synthetic O-Antigen of Vibrio cholerae O1, Serotype Inaba: Improved Synthesis of the Conjugation-ready Upstream Terminal Hexasaccharide Determinant. RSC Adv 2019; 9:36440-36454. [PMID: 33791092 PMCID: PMC8009174 DOI: 10.1039/c9ra08232h] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Synthesis of the upstream terminal hexasaccharide part of the lipopolysaccharides (LPS) of Vibrio cholerae O1, serotype Inaba has been improved. The key improvements include but are not limited to optimized conditions for the stereoselectivity of glycosylation reactions involved and fewer number of synthetic steps, compared to previous approaches. Particularly noteworthy is conducting the glycosylation of the very reactive glycosyl acceptor 8-azido-3,6-dioxaoctanol with the fully assembled hexasaccharide trichloroacetimidate under thermodynamic control. It produced the desired α glycoside with an α : β ratio of 7 : 1, compared with the ratio of 1.1 : 1, observed when the coupling was conducted conventionally. Several substances, which were previously obtained in purity acceptable only for synthetic intermediates, were now obtained in the analytically pure state and were fully characterized. The structure of the key trisaccharide glycosyl acceptor was confirmed by single-crystal X-ray structure determination. Improved synthesis of the conjugation-ready upstream terminal hexasaccharide determinant has been described with special reference to the stereoselectivity refinement.![]()
Collapse
Affiliation(s)
| | - Peng Xu
- LBC, NIDDK, National Institutes of Health, Bethesda, MD 20892-0815
| | - Edwin D Stevens
- Department of Chemistry, Western Kentucky University, Bowling Green, KY, 42101
| | - Pavol Kováč
- LBC, NIDDK, National Institutes of Health, Bethesda, MD 20892-0815
| |
Collapse
|
2
|
Markham JP, Wang B, Stevens ED, Burris SC, Deng Y. ortho
‐Alkylation of Pyridine
N
‐Oxides with Alkynes by Photocatalysis: Pyridine
N
‐Oxide as a Redox Auxiliary. Chemistry 2019; 25:6638-6644. [DOI: 10.1002/chem.201901065] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Jonathan P. Markham
- Chemistry DepartmentWestern Kentucky University 1906 College Heights Boulevard Bowling Green Kentucky 42101 USA
| | - Ban Wang
- Chemistry DepartmentWestern Kentucky University 1906 College Heights Boulevard Bowling Green Kentucky 42101 USA
| | - Edwin D. Stevens
- Chemistry DepartmentWestern Kentucky University 1906 College Heights Boulevard Bowling Green Kentucky 42101 USA
| | - Stuart C. Burris
- Chemistry DepartmentWestern Kentucky University 1906 College Heights Boulevard Bowling Green Kentucky 42101 USA
| | - Yongming Deng
- Chemistry DepartmentWestern Kentucky University 1906 College Heights Boulevard Bowling Green Kentucky 42101 USA
| |
Collapse
|
3
|
Key B, Arlinghaus R, Browman HI, Cooke SJ, Cowx IG, Diggles BK, Rose JD, Sawynok W, Schwab A, Skiftesvik AB, Stevens ED, Watson CA. Problems with equating thermal preference with 'emotional fever' and sentience: comment on 'Fish can show emotional fever: stress-induced hyperthermia in zebrafish' by Rey et al. (2015). Proc Biol Sci 2019; 284:rspb.2016.0681. [PMID: 28100812 PMCID: PMC5310028 DOI: 10.1098/rspb.2016.0681] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2016] [Accepted: 07/11/2016] [Indexed: 11/12/2022] Open
Affiliation(s)
- B Key
- Brain Growth and Regeneration Lab, School of Biomedical Sciences, The University of Queensland, Queensland 4072, Australia
| | - R Arlinghaus
- Dept Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries & Humboldt-Universität zu Berlin, 12587 Berlin, Germany
| | - H I Browman
- Institute of Marine Research, 5817 Storebø, Norway
| | - S J Cooke
- Dept Biology, Carleton University, Ottawa, Canada K1S 5B6
| | - I G Cowx
- Hull International Fisheries Institute, University of Hull, Hull, HU6 7RX, UK
| | - B K Diggles
- DigsFish Services, Banksia Beach, Queensland 4507, Australia
| | - J D Rose
- Dept Zoology and Physiology, University of Wyoming, Laramie, WY 82071, USA
| | - W Sawynok
- Infofish Australia, Frenchville, QLD 4701, Australia
| | - A Schwab
- Schwab & Sohn, 3507 Biglen, Switzerland
| | | | - E D Stevens
- Biomed Sci, Atlantic Veterinary College, Charlottetown, Canada C1A 4P3
| | - C A Watson
- Tropical Aquaculture Laboratory, University of Florida, Gainesville, FL 32611, USA
| |
Collapse
|
4
|
C. Tice N, Wild S, Olmstead C, D. Stevens E, Yan B, Brooks H, L. Jenkins J. Synthesis, Characterization, and Electronic and Structural Calculations of Some 1,4-Disubstituted Cyclopenta[d][1,2]oxazines. HETEROCYCLES 2019. [DOI: 10.3987/com-19-14184] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
5
|
Chatigny F, Groman DB, Martinson SA, Stevens ED. Evaluation of tissue changes following intramuscular infiltration of lidocaine in rainbow trout Oncorhynchus mykiss. J Fish Biol 2018; 92:888-900. [PMID: 29363141 DOI: 10.1111/jfb.13539] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2017] [Accepted: 12/11/2017] [Indexed: 06/07/2023]
Abstract
Rainbow trout Oncorhynchus mykiss were infiltrated with either saline or lidocaine adjacent to the dorsal fin to assess histopathological changes. Infiltration was done as if it were being used as a local anaesthetic. Tissue lesions and associated tissue healing were examined over a period of 30 days. Most changes occurred at the cranial site of where the solution was first infiltrated. The infiltration of a dose of 10 mg kg-1 of lidocaine appears to have damaged the skeletal muscle and connective tissues more than a similar volume of saline, especially during the first 15 days. The primary changes included haemorrhage, inflammation and muscle degeneration and necrosis. By day 30 post-infiltration inflammatory lesions were either nearly or completely absent, signs of myofibre regeneration were noted in only one fish. This experiment shows local anaesthetics and saline can produce localized tissue damage, especially during the first 2 weeks post infiltration. Care should be taken to allow the fish to heal for at least 30 days and probably more, no matter the solution administered, especially if giving repeated injections or infiltrations at the same site.
Collapse
Affiliation(s)
- F Chatigny
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, Prince Edward Island, C1A 4P3, Canada
| | - D B Groman
- Aquatic Diagnostic Services, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, Prince Edward Island, C1A 4P3, Canada
| | - S A Martinson
- Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, Prince Edward Island, C1A 4P3, Canada
| | - E D Stevens
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, 550 University Ave, Charlottetown, Prince Edward Island, C1A 4P3, Canada
| |
Collapse
|
6
|
Stevens ED, Arlinghaus R, Browman HI, Cooke SJ, Cowx IG, Diggles BK, Key B, Rose JD, Sawynok W, Schwab A, Skiftesvik AB, Watson CA, Wynne CDL. Stress is not pain. Comment on Elwood and Adams (2015) 'Electric shock causes physiological stress responses in shore crabs, consistent with prediction of pain'. Biol Lett 2016; 12:rsbl.2015.1006. [PMID: 27048466 DOI: 10.1098/rsbl.2015.1006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Accepted: 02/02/2016] [Indexed: 12/11/2022] Open
Affiliation(s)
- E D Stevens
- Department of Biomedical Science, Atlantic Veterinary College, Charlottetown, Prince Edward Island, Canada
| | - R Arlinghaus
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Humboldt-Universität zu Berlin, Berlin, Germany
| | - H I Browman
- Institute of Marine Research, Storebø, Norway
| | - S J Cooke
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - I G Cowx
- Hull International Fisheries Institute, University of Hull, Hull, Humberside, UK
| | | | - B Key
- Department of Biomedical Sciences, University of Queensland, St Lucia, Queensland, Australia
| | - J D Rose
- Department of Zoology and Physiology, University of Wyoming Laramie, WY, USA
| | - W Sawynok
- Infofish Australia, Frenchville, Australia
| | | | | | - C A Watson
- Tropical Aquaculture Laboratory, University of Florida, Gainesville, FL, USA
| | - C D L Wynne
- Department Psychology, Arizona State University, Tempe, AZ 85287, USA
| |
Collapse
|
7
|
Xu P, Stevens ED, French AD, Kováč P. Synthesis and molecular structure of the 5-methoxycarbonylpentyl α-glycoside of the upstream, terminal moiety of the O-specific polysaccharide of Vibrio cholerae O1, serotype Inaba. Molecules 2015; 20:2892-902. [PMID: 25679049 PMCID: PMC6272311 DOI: 10.3390/molecules20022892] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2015] [Accepted: 02/05/2015] [Indexed: 11/16/2022] Open
Abstract
The trimethylsilyl trifluoromethanesulfonate (TMSOTf)-catalyzed reaction of methyl 6-hydroxyhexanoate with 3-O-benzyl-4-(2,4-di-O-acetyl-3-deoxy-l-glycero-tetronamido)-4,6-dideoxy-2-O-levulinoyl-α-d-mannopyranosyl trichloroacetimidate followed by a two-step deprotection (hydrogenolysis over Pd/C catalyst and Zemplén deacylation, to simultaneously remove the acetyl and levulinoyl groups) gave 5-(methoxycarbonyl)pentyl 4-(3-deoxy-l-glycero-tetronamido)-4,6-dideoxy-α-d-mannopyranoside. The structure of the latter, for which crystals were obtained in the analytically pure state for the first time, followed from its NMR and high-resolution mass spectra and was confirmed by X-ray crystallography. The molecule has two approximately linear components; a line through the aglycon intersects a line through the mannosyl and tetronylamido groups at 120°. The crystal packing separates the aglycon groups from the tetronylamido and mannosyl groups, with only C-H…O hydrogen bonding among the aglycon groups and N-H…O, O-H…O and C-H…O links among the tetronylamido and mannosyl groups. A carbonyl oxygen atom accepts the strongest O-H…O hydrogen bond and two strong C-H…O hydrogen bonds. The geometric properties were compared with those of related molecules.
Collapse
Affiliation(s)
- Peng Xu
- NIDDK, LBC, National Institutes of Health, Bethesda, MD 20892-0815, USA.
| | - Edwin D Stevens
- Department of Chemistry, Western Kentucky University, 1906 College Heights Blvd., Bowling Green, KY 42101-1709, USA.
| | - Alfred D French
- Southern Regional Research Center, US Department of Agriculture, 1100 Robert E Lee Blvd, New Orleans, LA 70124, USA.
| | - Pavol Kováč
- NIDDK, LBC, National Institutes of Health, Bethesda, MD 20892-0815, USA.
| |
Collapse
|
8
|
|
9
|
Thaxton A, Izenwasser S, Wade D, Stevens ED, Mobley DL, Jaber V, Lomenzo SA, Trudell ML. 3-Aryl-3-arylmethoxyazetidines. A new class of high affinity ligands for monoamine transporters. Bioorg Med Chem Lett 2013; 23:4404-7. [PMID: 23806554 DOI: 10.1016/j.bmcl.2013.05.071] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 05/15/2013] [Accepted: 05/20/2013] [Indexed: 10/26/2022]
Abstract
A series of 3-aryl-3-arylmethoxy-azetidines were synthesized and evaluated for binding affinities at dopamine and serotonin transporters. The 3-aryl-3-arylmethoxyazetidines were generally SERT selective with the dichloro substituted congener 7c (Ki=1.0 nM) and the tetrachloro substituted derivative 7i (Ki=1.3 nM) possessing low nanomolar affinity for the SERT. The 3-(3,4-dichlorophenyl-3-phenylmethoxyazetidine (7g) exhibited moderate affinity at both DAT and SERT transporters and suggests that substitution of the aryl rings can be used to tune the mononamine transporter affinity.
Collapse
Affiliation(s)
- Amber Thaxton
- Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USA
| | | | | | | | | | | | | | | |
Collapse
|
10
|
Zelaya CA, Stevens ED, Dowd MK. Di(phenylpropylamino)gossypol: a derivative of the dimeric natural product gossypol. Acta Crystallogr C 2013; 69:439-43. [PMID: 23579723 DOI: 10.1107/s0108270113006288] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 03/05/2013] [Indexed: 11/10/2022] Open
Abstract
Di(phenylpropylamino)gossypol [systematic name: 2,2'-bis{1,6-dihydroxy-5-isopropyl-8-[(3-phenylpropylamino)methylidene]naphthalen-7-one}, C48H52N2O6, was formed by reaction of the dimeric natural product gossypol with 3-phenylpropylamine. The structure of this compound has its two naphthalene ring systems oriented approximately perpendicular to each other, and the two pendant phenylpropyl groups have different conformations. One of these side groups is considerably disordered at room temperature but less so at 120 K. The enantiomeric molecules form centrosymmetric dimers that are supported by intermolecular hydrogen bonds and by hydrophobic interactions between a pair of naphthalene rings. Two additional hydrogen bonds tie the dimer pairs into layers. Unlike gossypol and many gossypol Schiff base derivatives, the title compound crystallizes without the inclusion of solvent, which appears to occur because of the size and flexibility of its phenylpropyl pendent groups.
Collapse
Affiliation(s)
- Carlos A Zelaya
- Department of Chemistry, University of New Orleans, New Orleans, LA 70124, USA
| | | | | |
Collapse
|
11
|
Papudippu M, Shu H, Izenwasser S, Wade D, Gulasey G, Fournet S, Stevens ED, Lomenzo SA, Trudell ML. Regioselective synthesis and cannabinoid receptor binding affinity of N-alkylated 4,5-diaryl-1,2,3-triazoles. Med Chem Res 2012. [DOI: 10.1007/s00044-012-9991-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
12
|
Upadhyay SK, Creech CC, Bowdy KL, Stevens ED, Jursic BS, Neumann DM. Synthesis and antifungal activity of functionalized 2,3-spirostane isomers. Bioorg Med Chem Lett 2011; 21:2826-31. [PMID: 21489791 DOI: 10.1016/j.bmcl.2011.03.092] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 03/18/2011] [Accepted: 03/23/2011] [Indexed: 10/18/2022]
Abstract
Invasive fungal infections are a major complication for individuals with compromised immune systems. One of the most significant challenges in the treatment of invasive fungal infections is the increased resistance of many organisms to widely used antifungals, making the development of novel antifungal agents essential. Many naturally occurring products have been found to be effective antimicrobial agents. In particular, saponins with spirostane glycosidic moieties-isolated from plant or marine species-have been shown to possess a range of antimicrobial properties. In this report, we outline a novel approach to the synthesis of a number of functionalized spirostane molecules that can be further used as building blocks for novel spirostane-linked glycosides and present results from the in vitro screenings of the antifungal potential of each derivative against four fungal species, including Candida albicans, Cryptococcus neoformans, Candida glabrata, and the filamentous fungus Aspergillus fumigatus.
Collapse
|
13
|
Affiliation(s)
- Branko S. Jursic
- a Department of Chemistry , University of New Orleans , New Orleans, Louisiana, 70148, USA
| | - Edwin D. Stevens
- a Department of Chemistry , University of New Orleans , New Orleans, Louisiana, 70148, USA
| |
Collapse
|
14
|
|
15
|
|
16
|
Stevens ED, Dowd MK, Johnson GP, French AD. Experimental and theoretical electron density distribution of α,α-trehalose dihydrate. Carbohydr Res 2010; 345:1469-81. [DOI: 10.1016/j.carres.2010.03.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2010] [Revised: 03/10/2010] [Accepted: 03/14/2010] [Indexed: 10/19/2022]
|
17
|
Zhu N, Lightsey D, Liu J, Foroozesh M, Morgan KM, Stevens ED, Klein Stevens CL. Ethynyl and Propynylpyrene Inhibitors of Cytochrome P450. J Chem Crystallogr 2010; 40:343-352. [PMID: 20473363 PMCID: PMC2869100 DOI: 10.1007/s10870-009-9659-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The single-crystal X-ray structures and in vivo activities of three aryl acetylenic inhibitors of cytochromes P450 1A1, 1A2, 2A6, and 2B1 have been determined and are reported herein. These are 1-ethynylpyrene, 1-propy-nylpyrene, and 4-propynylpyrene. To investigate electronic influences on the mechanism of enzyme inhibition, the experimental electron density distribution of 1-ethynylpy-rene has been determined using low-temperature X-ray diffraction measurements, and the resulting net atomic charges compared with various theoretical calculations. A total of 82,390 reflections were measured with Mo Kα radiation to a (sinθ/λ)(max) = 0.985 Å(-1). Averaging symmetry equivalent reflections yielded 8,889 unique reflections. A least squares refinement procedure was used in which multipole parameters were added to describe the distortions of the atomic electron distributions from spherical symmetry. A map of the model electron density distribution of 1-ethynylpyrene was obtained. Net atomic charges calculated from refined monopole population parameters yielded charges that showed that the terminal acetylenic carbon atom (C18) is more negative than the internal carbon (C17). Net atomic charges calculated by ab initio, density functional theory, and semi-empirical methods are consistent with this trend suggesting that the terminal acetylenic carbon atom is more likely to be the site of oxidation. This is consistent with the inhibition mechanism pathway that results in the formation of a reactive ketene intermediate. This is also consistent with assay results that determined that 1-ethynylpyrene acts as a mechanism-based inhibitor of P450s 1A1 and 1A2 and as a reversible inhibitor of P450 2B1. Crystallographic data: 1-ethynylpyrene, C(18)H(10), P2(1)/c, a = 14.571(2) Å, b = 3.9094(5) Å, c = 20.242(3) Å, β = 105.042(2)°, V = 1,113.5(2) Å(3); 1-propynylpyrene, C(19)H(12), P2(1)/n, a = 8.970(2) Å, b = 10.136(1) Å, c = 14.080(3) Å, β = 99.77(2)°, V = 1,261.5(4) Å(3); 4-propynylpyrene, C(19)H(12), Pbca, a = 9.904(1) Å, b = 13.174(2) Å, c = 19.401(1) Å, V = 2,531.4(5) Å(3).
Collapse
Affiliation(s)
- Naijue Zhu
- Department of Chemistry, Xavier University of Louisiana, One Drexel Drive, New Orleans, LA 70125, USA
| | - Danielle Lightsey
- Department of Chemistry, Xavier University of Louisiana, One Drexel Drive, New Orleans, LA 70125, USA
| | - Jiawang Liu
- Department of Chemistry, Xavier University of Louisiana, One Drexel Drive, New Orleans, LA 70125, USA
| | - Maryam Foroozesh
- Department of Chemistry, Xavier University of Louisiana, One Drexel Drive, New Orleans, LA 70125, USA
| | - Kathleen M. Morgan
- Department of Chemistry, Xavier University of Louisiana, One Drexel Drive, New Orleans, LA 70125, USA
| | - Edwin D. Stevens
- Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USA
| | - Cheryl L. Klein Stevens
- Department of Chemistry, Xavier University of Louisiana, One Drexel Drive, New Orleans, LA 70125, USA
| |
Collapse
|
18
|
Fortman GC, Scott NM, Linden A, Stevens ED, Dorta R, Nolan SP. Unusual reactivities of N-heterocyclic carbenes upon coordination to the platinum(II)-dimethyl moiety. Chem Commun (Camb) 2010; 46:1050-2. [PMID: 20126709 DOI: 10.1039/b920482b] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Unsaturated NHCs of varying steric bulk undergo a series of unusual oxidative addition and reductive elimination processes upon binding to the Pt(Me)(2) fragment.
Collapse
Affiliation(s)
- George C Fortman
- EaStCHEM School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, UK
| | | | | | | | | | | |
Collapse
|
19
|
Díez-González S, Escudero-Adán EC, Benet-Buchholz J, Stevens ED, Slawin AMZ, Nolan SP. [(NHC)CuX] complexes: Synthesis, characterization and catalytic activities in reduction reactions and Click Chemistry. On the advantage of using well-defined catalytic systems. Dalton Trans 2010; 39:7595-606. [DOI: 10.1039/c0dt00218f] [Citation(s) in RCA: 182] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
20
|
Affiliation(s)
- Sylvain Gaillard
- School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, United Kingdom
| | | | - Allen T. Bonura
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148
| | - Edwin D. Stevens
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148
| | - Steven P. Nolan
- School of Chemistry, University of St Andrews, St Andrews, KY16 9ST, United Kingdom
| |
Collapse
|
21
|
Kaur H, Izenwasser S, Verma A, Wade D, Housman A, Stevens ED, Mobley DL, Trudell ML. Synthesis and monoamine transporter affinity of 3alpha-arylmethoxy-3beta-arylnortropanes. Bioorg Med Chem Lett 2009; 19:6865-8. [PMID: 19896846 DOI: 10.1016/j.bmcl.2009.10.087] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2009] [Revised: 10/16/2009] [Accepted: 10/20/2009] [Indexed: 10/20/2022]
Abstract
A series of 3-arylnortrop-2-enes and 3alpha-arylmethoxy-3beta-arylnortropanes were synthesized and evaluated for binding affinity at monoamine transporters. The 3-(3,4-dichlorophenyl)nortrop-2-ene (6e) exhibited high affinity for the SERT (K(i)=0.3 nM). The 3alpha-arylmethoxy-3beta-arylnortropanes were generally SERT selective with the 3alpha-(3.4-dichlorophenylmethoxy)-3betaphenylnortrop-2-ene (7c) possessing subnanomolar potency (K(i)=0.061 nM). However, 3alpha-(3,4-dichlorophenylmethoxy)-3beta-phenylnortrop-2-ene (7b) exhibited high affinity at all three transporters [(DAT K(i)=22 nM), (SERT K(i)=6 nM) and (NET K(i)=101 nM)].
Collapse
Affiliation(s)
- Harneet Kaur
- Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USA
| | | | | | | | | | | | | | | |
Collapse
|
22
|
Verma A, Stevens ED. N-(4-Hydroxy-phen-yl)-2-(1,1,3-trioxo-2,3-di-hydro-1,2-benzothia-zol-2-yl)-acet-amide. Acta Crystallogr Sect E Struct Rep Online 2009; 65:o1667. [PMID: 21582927 PMCID: PMC2969438 DOI: 10.1107/s1600536809023022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2009] [Accepted: 06/15/2009] [Indexed: 11/24/2022]
Abstract
In the title compound, C(15)H(12)N(2)O(5)S, the benzisothia-zole group is approximately planar (r.m.s. deviation excluding H atoms and the two O atoms bonded to S = 0.023 Å). The dihedral angle between the benzisothia-zole ring and the terminal phenol ring is 84.9 (1)°. In the crystal, mol-ecules are joined by N-H⋯O and O-H⋯O hydrogen bonds, and π-stacking inter-actions are observed between alternating phenol and benzisothia-zole rings [centroid-centroid distances = 3.929 (3) and 3.943 (3) Å].
Collapse
Affiliation(s)
- Abha Verma
- Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USA
| | - Edwin D. Stevens
- Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USA
| |
Collapse
|
23
|
Cheng J, Xu L, Stevens ED, Trudell ML, Izenwasser S, Wade D. Stereoselective synthesis of conformationally constrained tropane analogues: 6-Chloro-2,5-diazatetracyclo[8.5.0.02,13.04,9]pentadeca-4,6,8-triene-11-one and 6-chloro-2,7-diazatetracyclo-[8.5.0.02,13.04,9]pentadeca-4,6,8-triene-11-one. J Heterocycl Chem 2009. [DOI: 10.1002/jhet.5570410414] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
24
|
Shu H, Izenwasser S, Wade D, Stevens ED, Trudell ML. Synthesis and CB1 cannabinoid receptor affinity of 4-alkoxycarbonyl-1,5-diaryl-1,2,3-triazoles. Bioorg Med Chem Lett 2009; 19:891-3. [PMID: 19097888 PMCID: PMC2631625 DOI: 10.1016/j.bmcl.2008.11.110] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Revised: 11/24/2008] [Accepted: 11/26/2008] [Indexed: 11/19/2022]
Abstract
A series of 4-alkoxycarbonyl-1,5-diaryl-1,2,3-triazoles were synthesized regioselectively using click chemistry and evaluated at CB1 cannabinoid receptors. The n-propyl ester 11 (K(i)=4.6 nM) and phenyl ester 14 (K(i)=11 nM) exhibited the most potent affinity of the series.
Collapse
Affiliation(s)
- Hong Shu
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, LA 70148, USA
| | | | | | | | | |
Collapse
|
25
|
Cheuk S, Stevens ED, Wang G. Synthesis and structural analysis of a series of D-glucose derivatives as low molecular weight gelators. Carbohydr Res 2008; 344:417-25. [PMID: 19154993 DOI: 10.1016/j.carres.2008.12.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2008] [Revised: 11/27/2008] [Accepted: 12/02/2008] [Indexed: 11/15/2022]
Abstract
Low molecular weight gelators are an interesting new type of compounds that are important in supramolecular chemistry and advanced materials. Previously, we had synthesized several acyl derivatives of methyl 4,6-O-benzylidene-alpha-D-glucopyranoside and found that a number of terminal acetylene-containing esters are good gelators. To understand the structure requirement of the acyl chains, we synthesized a series of analogs containing different functional groups including aryl, alkenyl, and halogen derivatives. X-ray crystal structures of a monoester and a diester derivative were also obtained to help understand the relationship between structure and gelation. For good gelation properties, the carboxyl derivatives should possess alkyl groups containing a terminal acetylene group and aryl derivatives.
Collapse
Affiliation(s)
- Sherwin Cheuk
- Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USA
| | | | | |
Collapse
|
26
|
Scott NM, Clavier H, Mahjoor P, Stevens ED, Nolan SP. Synthetic, Structural, and Thermochemical Studies of N-Heterocyclic Carbene (NHC) and Tertiary Phosphine Ligands in the [(L)2Ni(CO)2] (L = PR3, NHC) System. Organometallics 2008. [DOI: 10.1021/om8001125] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Natalie M. Scott
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, and Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain
| | - Hervé Clavier
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, and Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain
| | - Parisa Mahjoor
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, and Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain
| | - Edwin D. Stevens
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, and Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain
| | - Steven P. Nolan
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, and Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain
| |
Collapse
|
27
|
|
28
|
Kelly III RA, Clavier H, Giudice S, Scott NM, Stevens ED, Bordner J, Samardjiev I, Hoff CD, Cavallo L, Nolan SP. Determination of N-Heterocyclic Carbene (NHC) Steric and Electronic Parameters using the [(NHC)Ir(CO)2Cl] System. Organometallics 2007. [DOI: 10.1021/om701001g] [Citation(s) in RCA: 506] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Roy A. Kelly III
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148, Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Dipartmento of Chimica, Universitá di Salerno, Via Ponte don Melillo, Fisciano (SA), I-84084, Italy, Department of Chemistry, University of Miami, Coral Gables, Florida 33124, and Pfizer Global Research and Development, Groton, Connecticut 06340
| | - Hervé Clavier
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148, Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Dipartmento of Chimica, Universitá di Salerno, Via Ponte don Melillo, Fisciano (SA), I-84084, Italy, Department of Chemistry, University of Miami, Coral Gables, Florida 33124, and Pfizer Global Research and Development, Groton, Connecticut 06340
| | - Simona Giudice
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148, Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Dipartmento of Chimica, Universitá di Salerno, Via Ponte don Melillo, Fisciano (SA), I-84084, Italy, Department of Chemistry, University of Miami, Coral Gables, Florida 33124, and Pfizer Global Research and Development, Groton, Connecticut 06340
| | - Natalie M. Scott
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148, Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Dipartmento of Chimica, Universitá di Salerno, Via Ponte don Melillo, Fisciano (SA), I-84084, Italy, Department of Chemistry, University of Miami, Coral Gables, Florida 33124, and Pfizer Global Research and Development, Groton, Connecticut 06340
| | - Edwin D. Stevens
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148, Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Dipartmento of Chimica, Universitá di Salerno, Via Ponte don Melillo, Fisciano (SA), I-84084, Italy, Department of Chemistry, University of Miami, Coral Gables, Florida 33124, and Pfizer Global Research and Development, Groton, Connecticut 06340
| | - Jon Bordner
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148, Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Dipartmento of Chimica, Universitá di Salerno, Via Ponte don Melillo, Fisciano (SA), I-84084, Italy, Department of Chemistry, University of Miami, Coral Gables, Florida 33124, and Pfizer Global Research and Development, Groton, Connecticut 06340
| | - Ivan Samardjiev
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148, Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Dipartmento of Chimica, Universitá di Salerno, Via Ponte don Melillo, Fisciano (SA), I-84084, Italy, Department of Chemistry, University of Miami, Coral Gables, Florida 33124, and Pfizer Global Research and Development, Groton, Connecticut 06340
| | - Carl D. Hoff
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148, Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Dipartmento of Chimica, Universitá di Salerno, Via Ponte don Melillo, Fisciano (SA), I-84084, Italy, Department of Chemistry, University of Miami, Coral Gables, Florida 33124, and Pfizer Global Research and Development, Groton, Connecticut 06340
| | - Luigi Cavallo
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148, Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Dipartmento of Chimica, Universitá di Salerno, Via Ponte don Melillo, Fisciano (SA), I-84084, Italy, Department of Chemistry, University of Miami, Coral Gables, Florida 33124, and Pfizer Global Research and Development, Groton, Connecticut 06340
| | - Steven P. Nolan
- Department of Chemistry, University of New Orleans, 2000 Lakeshore Drive, New Orleans, Louisiana 70148, Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Dipartmento of Chimica, Universitá di Salerno, Via Ponte don Melillo, Fisciano (SA), I-84084, Italy, Department of Chemistry, University of Miami, Coral Gables, Florida 33124, and Pfizer Global Research and Development, Groton, Connecticut 06340
| |
Collapse
|
29
|
Díez-González S, Stevens ED, Scott NM, Petersen JL, Nolan SP. Synthesis and Characterization of [Cu(NHC)2]X Complexes: Catalytic and Mechanistic Studies of Hydrosilylation Reactions. Chemistry 2007; 14:158-68. [PMID: 17999393 DOI: 10.1002/chem.200701013] [Citation(s) in RCA: 136] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Silvia Díez-González
- Institute of Chemical Research of Catalonia (ICIQ), Av. Països Catalans, 16, 43007 Tarragona, Spain.
| | | | | | | | | |
Collapse
|
30
|
Ong KJ, Stevens ED, Wright PA. Gill morphology of the mangrove killifish (Kryptolebias marmoratus) is plastic and changes in response to terrestrial air exposure. ACTA ACUST UNITED AC 2007; 210:1109-15. [PMID: 17371909 DOI: 10.1242/jeb.002238] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Amphibious mangrove killifish, Kryptolebias marmoratus (formerly Rivulus marmoratus), are frequently exposed to aerial conditions in their natural environment. We tested the hypothesis that gill structure is plastic and that metabolic rate is maintained in response to air exposure. During air exposure, when gills are no longer functional, we predicted that gill surface area would decrease. In the first experiment, K. marmoratus were exposed to either water (control) or air for 1 h, 1 day, 1 week, or 1 week followed by a return to water for 1 week (recovery). Scanning electron micrographs (SEM) and light micrographs of gill sections were taken, and morphometric analyses of lamellar width, lamellar length and interlamellar cell mass (ILCM) height were performed. Following 1 week of air exposure, SEM indicated that there was a decrease in lamellar surface area. Morphometric analysis of light micrographs revealed that there were significant changes in the height of the ILCM, but there were no significant differences in lamellae width and length between any of the treatments. Following 1 week of recovery in water, the ILCM regressed and gill lamellae were similar to control fish, indicating that the morphological changes were reversible. In the second experiment, V(CO(2)) was measured in fish continuously over a 5-day period in air and compared with previous measurements of oxygen uptake (V(O(2))) in water. V(CO(2)) varied between 6 and 10 micromol g(-1) h(-1) and was significantly higher on days 3, 4 and 5 relative to days 1 and 2. In contrast to V(O(2)) in water, V(CO(2)) in air showed no diurnal rhythm over a 24 h period. These findings indicate that K. marmoratus remodel their gill structures in response to air exposure and that these changes are completely reversible. Furthermore, over a similar time frame, changes in V(CO(2)) indicate that metabolic rate is maintained at a rate comparable to that of fish in water, underlying the remarkable ability of K. marmoratus to thrive in both aquatic and terrestrial habitats.
Collapse
Affiliation(s)
- K J Ong
- Department of Integrative Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | | | | |
Collapse
|
31
|
Johnson GP, Stevens ED, French AD. Octa-O-propanoyl-β-maltose: crystal structure, acyl stacking, related structures, and conformational analysis. Carbohydr Res 2007; 342:1210-22. [PMID: 17383618 DOI: 10.1016/j.carres.2007.02.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 02/21/2007] [Accepted: 02/22/2007] [Indexed: 10/23/2022]
Abstract
The crystal structure of beta-maltose octapropanoate (1) was solved to improve understanding of di-, oligo-, and polysaccharide conformations. The O6 and O6' atoms are in gg and gt orientations, respectively. Extrapolation of the coordinates of the non-reducing residue and observed linkage bond and torsion angles of 1 [Formula: see text] yields a left-handed helix similar to amylose triacetate I. The phi and psi values of 1 are also similar to those of other crystalline, acylated maltose compounds as well as some hydroxyl-bearing molecules. Acylated maltose moieties are often stabilized by stacking of the carbonyl groups and alpha-carbons on O3 and O2' as well as by the exo-anomeric effect. The conformation of 1 is within the 1-kcal/mol contour on a hybrid energy map built with a dielectric constant of 7.5, but corresponds to higher energies on maps made with lower dielectric constants. In one region of phi,psi space, both hydroxyl-bearing and derivatized maltose moieties are found but no inter-residue, intramolecular hydrogen-bonding occurs. In another region, only hydroxyl-bearing molecules crystallize and O2'...O3 hydrogen bonds are always found. In agreement with the energy surfaces, amylose helices extrapolated from available linkage geometries were almost all left-handed.
Collapse
Affiliation(s)
- Glenn P Johnson
- Southern Regional Research Center, US Department of Agriculture, 1100 Robert E. Lee Blvd., New Orleans, LA 70124, United States
| | | | | |
Collapse
|
32
|
Marion N, Escudero-Adán EC, Benet-Buchholz J, Stevens ED, Fensterbank L, Malacria M, Nolan SP. Synthesis, Characterization, and Structure of [GaCl3(NHC)] Complexes. Organometallics 2007. [DOI: 10.1021/om070241g] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Nicolas Marion
- Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Chemistry Department, University of New Orleans, New Orleans, Louisiana 70148, and Laboratoire de Chimie Organique, UMR CNRS 7611, Institut de Chimie Moléculaire FR 2769, Université Pierre et Marie Curie, Paris 6, Tour 44-54 case 229, 4 place Jussieu, 75005 Paris, France
| | - Eduardo C. Escudero-Adán
- Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Chemistry Department, University of New Orleans, New Orleans, Louisiana 70148, and Laboratoire de Chimie Organique, UMR CNRS 7611, Institut de Chimie Moléculaire FR 2769, Université Pierre et Marie Curie, Paris 6, Tour 44-54 case 229, 4 place Jussieu, 75005 Paris, France
| | - Jordi Benet-Buchholz
- Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Chemistry Department, University of New Orleans, New Orleans, Louisiana 70148, and Laboratoire de Chimie Organique, UMR CNRS 7611, Institut de Chimie Moléculaire FR 2769, Université Pierre et Marie Curie, Paris 6, Tour 44-54 case 229, 4 place Jussieu, 75005 Paris, France
| | - Edwin D. Stevens
- Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Chemistry Department, University of New Orleans, New Orleans, Louisiana 70148, and Laboratoire de Chimie Organique, UMR CNRS 7611, Institut de Chimie Moléculaire FR 2769, Université Pierre et Marie Curie, Paris 6, Tour 44-54 case 229, 4 place Jussieu, 75005 Paris, France
| | - Louis Fensterbank
- Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Chemistry Department, University of New Orleans, New Orleans, Louisiana 70148, and Laboratoire de Chimie Organique, UMR CNRS 7611, Institut de Chimie Moléculaire FR 2769, Université Pierre et Marie Curie, Paris 6, Tour 44-54 case 229, 4 place Jussieu, 75005 Paris, France
| | - Max Malacria
- Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Chemistry Department, University of New Orleans, New Orleans, Louisiana 70148, and Laboratoire de Chimie Organique, UMR CNRS 7611, Institut de Chimie Moléculaire FR 2769, Université Pierre et Marie Curie, Paris 6, Tour 44-54 case 229, 4 place Jussieu, 75005 Paris, France
| | - Steven P. Nolan
- Institute of Chemical Research of Catalonia (ICIQ), Avenida Països Catalans 16, 43007 Tarragona, Spain, Chemistry Department, University of New Orleans, New Orleans, Louisiana 70148, and Laboratoire de Chimie Organique, UMR CNRS 7611, Institut de Chimie Moléculaire FR 2769, Université Pierre et Marie Curie, Paris 6, Tour 44-54 case 229, 4 place Jussieu, 75005 Paris, France
| |
Collapse
|
33
|
Jursic BS, Sagiraju S, Ancalade DK, Clark T, Stevens ED. Practical Preparation of Z‐α‐(N‐Acetylamino)‐ and Z‐α‐(N‐Benzoylamino)‐α,β‐unsaturated Acids. SYNTHETIC COMMUN 2007. [DOI: 10.1080/00397910701265895] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Branko S. Jursic
- a Department of Chemistry , University of New Orleans , New Orleans, Louisiana
| | - Sarada Sagiraju
- a Department of Chemistry , University of New Orleans , New Orleans, Louisiana
| | - Dustin K. Ancalade
- a Department of Chemistry , University of New Orleans , New Orleans, Louisiana
| | - Traneil Clark
- a Department of Chemistry , University of New Orleans , New Orleans, Louisiana
| | - Edwin D. Stevens
- a Department of Chemistry , University of New Orleans , New Orleans, Louisiana
| |
Collapse
|
34
|
de Frémont P, Singh R, Stevens ED, Petersen JL, Nolan SP. Synthesis, Characterization and Reactivity of N-Heterocyclic Carbene Gold(III) Complexes. Organometallics 2007. [DOI: 10.1021/om060887t] [Citation(s) in RCA: 173] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Pierre de Frémont
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Institut Català d'Investigació Química, Av. Països Catalans 16, 43007, Tarragona, Spain, and Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506
| | - Rohit Singh
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Institut Català d'Investigació Química, Av. Països Catalans 16, 43007, Tarragona, Spain, and Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506
| | - Edwin D. Stevens
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Institut Català d'Investigació Química, Av. Països Catalans 16, 43007, Tarragona, Spain, and Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506
| | - Jeffrey L. Petersen
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Institut Català d'Investigació Química, Av. Països Catalans 16, 43007, Tarragona, Spain, and Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506
| | - Steven P. Nolan
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Institut Català d'Investigació Química, Av. Països Catalans 16, 43007, Tarragona, Spain, and Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506
| |
Collapse
|
35
|
de Frémont P, Stevens ED, Eelman MD, Fogg DE, Nolan SP. Synthesis and Characterization of Gold(I) N-Heterocyclic Carbene Complexes Bearing Biologically Compatible Moieties. Organometallics 2006. [DOI: 10.1021/om060733d] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Pierre de Frémont
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, and Center for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, K1N 6N5, Canada
| | - Edwin D. Stevens
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, and Center for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, K1N 6N5, Canada
| | - Melanie D. Eelman
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, and Center for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, K1N 6N5, Canada
| | - Deryn E. Fogg
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, and Center for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, K1N 6N5, Canada
| | - Steven P. Nolan
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, and Center for Catalysis Research and Innovation, Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, K1N 6N5, Canada
| |
Collapse
|
36
|
Affiliation(s)
- Michael K. Dowd
- a Southern Regional Research Center , ARS , USDA , 1100 Robert E. Lee Blvd., New Orleans, Lousiana, USA
| | - Edwin D. Stevens
- b Department of Chemistry , University of New Orleans , New Orleans, Lousiana, USA
| |
Collapse
|
37
|
Malyshev DA, Scott NM, Marion N, Stevens ED, Ananikov VP, Beletskaya IP, Nolan SP. Homogeneous Nickel Catalysts for the Selective Transfer of a Single Arylthio Group in the Catalytic Hydrothiolation of Alkynes. Organometallics 2006. [DOI: 10.1021/om060302v] [Citation(s) in RCA: 148] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Denis A. Malyshev
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow, 119991, Russia, and Chemistry Department, Lomonosov Moscow State University, Vorob'evy gory, Moscow, 119899, Russia
| | - Natalie M. Scott
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow, 119991, Russia, and Chemistry Department, Lomonosov Moscow State University, Vorob'evy gory, Moscow, 119899, Russia
| | - Nicolas Marion
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow, 119991, Russia, and Chemistry Department, Lomonosov Moscow State University, Vorob'evy gory, Moscow, 119899, Russia
| | - Edwin D. Stevens
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow, 119991, Russia, and Chemistry Department, Lomonosov Moscow State University, Vorob'evy gory, Moscow, 119899, Russia
| | - Valentine P. Ananikov
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow, 119991, Russia, and Chemistry Department, Lomonosov Moscow State University, Vorob'evy gory, Moscow, 119899, Russia
| | - Irina P. Beletskaya
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow, 119991, Russia, and Chemistry Department, Lomonosov Moscow State University, Vorob'evy gory, Moscow, 119899, Russia
| | - Steven P. Nolan
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky Prospect 47, Moscow, 119991, Russia, and Chemistry Department, Lomonosov Moscow State University, Vorob'evy gory, Moscow, 119899, Russia
| |
Collapse
|
38
|
Marion N, Navarro O, Mei J, Stevens ED, Scott NM, Nolan SP. Modified (NHC)Pd(allyl)Cl (NHC = N-heterocyclic carbene) complexes for room-temperature Suzuki-Miyaura and Buchwald-Hartwig reactions. J Am Chem Soc 2006; 128:4101-11. [PMID: 16551119 DOI: 10.1021/ja057704z] [Citation(s) in RCA: 744] [Impact Index Per Article: 41.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of (NHC)Pd(R-allyl)Cl complexes [NHC: IPr = N,N'-bis(2,6-diisopropylphenyl)imidazol-2-ylidene, SIPr = N,N'-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene; R = H, Me, gem-Me2, Ph] have been synthesized and fully characterized. When compared to (NHC)Pd(allyl)Cl, substitution at the terminal position of the allyl scaffold favors a more facile activation step. This translates into higher catalytic activity in the Suzuki-Miyaura and Buchwald-Hartwig reactions, allowing for the coupling of unactivated aryl chlorides at room temperature in minutes. In the Suzuki-Miyaura reaction, aryl triflates, bromides, and chlorides react with boronic acids using very low catalyst loading. In the N-aryl amination reaction, a wide range of substrates has been coupled efficiently; primary-, secondary-, alkyl-, or aryl-amines react in high yields with unactivated, neutral, and activated aryl chlorides and bromides. In both reactions, extremely hindered substrates such as tri-ortho-substituted biaryls and tetra-ortho-substituted diarylamines can be produced without loss of activity. Finally, the present catalytic system has proven to be efficient with as low as 10 parts-per-million (ppm) of precatalyst in the Buchwald-Hartwig reaction and 50 ppm in the Suzuki-Miyaura reaction.
Collapse
Affiliation(s)
- Nicolas Marion
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, USA
| | | | | | | | | | | |
Collapse
|
39
|
MacKinnon CA, Lawson A, Stevens ED, Brooks RJ. Body temperature fluctuations in free-ranging eastern foxsnakes (Elaphe gloydi) during cold-water swimming. CAN J ZOOL 2006. [DOI: 10.1139/z05-168] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We examined the thermal biology of free-ranging terrestrial eastern foxsnakes (Elaphe gloydi Conant, 1940) that were voluntarily swimming in cold water during spring, in Georgian Bay, Ontario, Canada. Using temperature-sensitive radiotelemetry, we recorded body temperatures of foxsnakes during 12 cold-water swims, and subsequent warming on shore. During these swims, water temperatures were from 11 to 22 °C and distances of 85–1330 m were travelled. Snakes that were in cold water long enough equilibrated with water temperature and did not maintain a body temperature above ambient. The largest observed drop in body temperature was 22.6 °C (over 11 min) and the largest increase was 23 °C (over 66 min). Such large, rapid temperature fluctuations have not previously been reported in detail from snakes in the field. Twice as many telemetry observations as expected occurred between 1200 and 1400, suggesting that snakes chose to swim midday. Additionally, our results suggest that foxsnakes bask to raise their body temperature prior to swimming in cold water. We compared swimming speed and the coefficient of temperature change among foxsnakes and other snake species. Swimming speed was positively correlated with water temperature, similar to other findings. We found no clear trend between mass and the coefficients of cooling and warming; however, snakes cooled in water 2.8–8.6 times faster than they warmed in air.
Collapse
|
40
|
de Frémont P, Stevens ED, Fructos MR, Mar Díaz-Requejo M, Pérez PJ, Nolan SP. Synthesis, isolation and characterization of cationic gold(i) N-heterocyclic carbene (NHC) complexes. Chem Commun (Camb) 2006:2045-7. [PMID: 16767270 DOI: 10.1039/b601547f] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A number of cationic gold(I) complexes have been synthesized and found to be stabilized by the use of N-heterocyclic carbene ligands. These species are often employed as in situ-generated reactive intermediates in gold catalyzed organic transformations. An isolated, well-defined species was tested in gold-mediated carbene transfer reactions from ethyl diazoacetate.
Collapse
Affiliation(s)
- Pierre de Frémont
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, USA
| | | | | | | | | | | |
Collapse
|
41
|
Marion N, de Frémont P, Lemière G, Stevens ED, Fensterbank L, Malacria M, Nolan SP. AuI-catalyzed cycloisomerization of 1,5-enynes bearing a propargylic acetate: formation of unexpected bicyclo[3.1.0]hexene. Chem Commun (Camb) 2006:2048-50. [PMID: 16767271 DOI: 10.1039/b602839j] [Citation(s) in RCA: 123] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The use of N-heterocyclic carbene (NHC) as a ligand in the gold(I)-catalyzed cycloisomerization of enyne results in the assembly of a new carbocyclic product.
Collapse
Affiliation(s)
- Nicolas Marion
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, USA
| | | | | | | | | | | | | |
Collapse
|
42
|
de Frémont P, Scott NM, Stevens ED, Ramnial T, Lightbody OC, Macdonald CLB, Clyburne JAC, Abernethy CD, Nolan SP. Synthesis of Well-Defined N-Heterocyclic Carbene Silver(I) Complexes. Organometallics 2005. [DOI: 10.1021/om050735i] [Citation(s) in RCA: 281] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Pierre de Frémont
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada, Department of Chemistry and Biochemistry University of Windsor, 273-1 Essex Hall, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada and Department of Chemistry, Keene State College, Keene, New Hampshire 03435-2001
| | - Natalie M. Scott
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada, Department of Chemistry and Biochemistry University of Windsor, 273-1 Essex Hall, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada and Department of Chemistry, Keene State College, Keene, New Hampshire 03435-2001
| | - Edwin D. Stevens
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada, Department of Chemistry and Biochemistry University of Windsor, 273-1 Essex Hall, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada and Department of Chemistry, Keene State College, Keene, New Hampshire 03435-2001
| | - Taramatee Ramnial
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada, Department of Chemistry and Biochemistry University of Windsor, 273-1 Essex Hall, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada and Department of Chemistry, Keene State College, Keene, New Hampshire 03435-2001
| | - Owen C. Lightbody
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada, Department of Chemistry and Biochemistry University of Windsor, 273-1 Essex Hall, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada and Department of Chemistry, Keene State College, Keene, New Hampshire 03435-2001
| | - Charles L. B. Macdonald
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada, Department of Chemistry and Biochemistry University of Windsor, 273-1 Essex Hall, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada and Department of Chemistry, Keene State College, Keene, New Hampshire 03435-2001
| | - Jason A. C. Clyburne
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada, Department of Chemistry and Biochemistry University of Windsor, 273-1 Essex Hall, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada and Department of Chemistry, Keene State College, Keene, New Hampshire 03435-2001
| | - Colin D. Abernethy
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada, Department of Chemistry and Biochemistry University of Windsor, 273-1 Essex Hall, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada and Department of Chemistry, Keene State College, Keene, New Hampshire 03435-2001
| | - Steven P. Nolan
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada, Department of Chemistry and Biochemistry University of Windsor, 273-1 Essex Hall, 401 Sunset Avenue, Windsor, Ontario N9B 3P4, Canada and Department of Chemistry, Keene State College, Keene, New Hampshire 03435-2001
| |
Collapse
|
43
|
Kelly RA, Scott NM, Díez-González S, Stevens ED, Nolan SP. Simple Synthesis of CpNi(NHC)Cl Complexes (Cp = Cyclopentadienyl; NHC = N-Heterocyclic Carbene). Organometallics 2005. [DOI: 10.1021/om0501879] [Citation(s) in RCA: 147] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Roy A. Kelly
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148
| | - Natalie M. Scott
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148
| | - Silvia Díez-González
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148
| | - Edwin D. Stevens
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148
| | - Steven P. Nolan
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148
| |
Collapse
|
44
|
Díez-González S, Kaur H, Zinn FK, Stevens ED, Nolan SP. A Simple and Efficient Copper-Catalyzed Procedure for the Hydrosilylation of Hindered and Functionalized Ketones. J Org Chem 2005; 70:4784-96. [PMID: 15932319 DOI: 10.1021/jo050397v] [Citation(s) in RCA: 187] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The catalytic hydrosilylation of highly hindered and functionalized ketones is described. The combination of inexpensive catalyst precursors, CuCl and NHC.HX (NHC = N-heterocyclic carbene), leads to a highly efficient reduction mediator for the preparation of silyl ethers from unfunctionalized and functionalized alkyl, cyclic, bicyclic, aromatic, and heteroaromatic ketones. A series of catalyst precursors have been structurally characterized and a catalyst-structure activity relationship is discussed.
Collapse
Affiliation(s)
- Silvia Díez-González
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, USA
| | | | | | | | | |
Collapse
|
45
|
Scott NM, Pons V, Stevens ED, Heinekey DM, Nolan SP. An Electron-Deficient Iridium(III) Dihydride Complex Capable of Intramolecular CH Activation. Angew Chem Int Ed Engl 2005. [DOI: 10.1002/ange.200463000] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
46
|
Scott NM, Pons V, Stevens ED, Heinekey DM, Nolan SP. An Electron-Deficient Iridium(III) Dihydride Complex Capable of Intramolecular CH Activation. Angew Chem Int Ed Engl 2005; 44:2512-5. [PMID: 15782375 DOI: 10.1002/anie.200463000] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- Natalie M Scott
- Department of Chemistry, University of New Orleans, New Orleans, LA 70148, USA
| | | | | | | | | |
Collapse
|
47
|
Affiliation(s)
- Pierre de Frémont
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148
| | - Natalie M. Scott
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148
| | - Edwin D. Stevens
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148
| | - Steven P. Nolan
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148
| |
Collapse
|
48
|
Ford ZM, Stevens ED, Johnson GP, French AD. Determining the crystal structure of cellulose IIII by modeling. Carbohydr Res 2005; 340:827-33. [PMID: 15780248 DOI: 10.1016/j.carres.2005.01.028] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2004] [Accepted: 01/21/2005] [Indexed: 11/24/2022]
Abstract
Recently, a one-chain monoclinic unit cell for cellulose III(I) having P2(1) symmetry and a single glucose in the asymmetric unit was proposed, based on high-resolution diffraction patterns. The new work challenged a two-chain structure that was published 25 years earlier, although it did not provide new three-dimensional coordinates. Our goals were to solve the structure by modeling, find whether modeling would reject the previously determined two-chain unit cell, and compare the model with the anticipated experimental structure. Combinations of three rotamers of the O-2, O-3, and O-6 hydroxyl groups produced 27 'up' and 27 'down' starting structures. Clusters ('minicrystals') of 13 cellotetraose chains terminated by methyl groups for each of the 54 starting structures were optimized with MM3(96). Hydroxyl groups on 16 of these 54 structures reoriented to give very similar hydrogen-bonding schemes in the interiors, along with the lowest energies. Hydrogen bonds included the usual intramolecular O-3H...O-5' linkage, with O-6' also accepting from O-3H. Interchain hydrogen bonds form an infinite, cooperative O-6H...O-2H...O-6 network. Direct comparison of total minicrystal energies for the one- and two-chain unit cell was inappropriate because the two-chain cell's alternate chains are shifted 0.9 A along the z-axis. To get comparable energy values, models were built with both cellotetraose and cellohexaose chains. The differences in their energies represent the energies for the central layers of cellobiose units. The one-chain cell models had much lower energy. The eight best 'up' one-chain models agree reasonably well with the structure newly determined by experiment.
Collapse
Affiliation(s)
- Zakhia M Ford
- Department of Chemistry, University of New Orleans, New Orleans, LA 70124, USA
| | | | | | | |
Collapse
|
49
|
Scott NM, Dorta R, Stevens ED, Correa A, Cavallo L, Nolan SP. Interaction of a Bulky N-Heterocyclic Carbene Ligand with Rh(I) and Ir(I). Double C−H Activation and Isolation of Bare 14-Electron Rh(III) and Ir(III) Complexes. J Am Chem Soc 2005; 127:3516-26. [PMID: 15755173 DOI: 10.1021/ja043249f] [Citation(s) in RCA: 266] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Reactivity and structural studies of unusual rhodium and iridium systems bearing two N-heterocyclic carbene (NHC) ligands are presented. These systems are capable of intramolecular C-H bond activation and lead to coordinatively unsaturated 16-electron complexes. The resulting complexes can be further unsaturated by simple halide abstraction, leading to 14-electron species bearing an all-carbon environment. Saturation of the vacant sites in the 16- and 14-electron complexes with carbon monoxide permits a structural comparison. DFT calculations show that these electrophilic metal centers are stabilized by pi-donation of the NHC ligands.
Collapse
Affiliation(s)
- Natalie M Scott
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, USA
| | | | | | | | | | | |
Collapse
|
50
|
Dorta R, Stevens ED, Scott NM, Costabile C, Cavallo L, Hoff CD, Nolan SP. Steric and Electronic Properties of N-Heterocyclic Carbenes (NHC): A Detailed Study on Their Interaction with Ni(CO)4. J Am Chem Soc 2005; 127:2485-95. [PMID: 15725003 DOI: 10.1021/ja0438821] [Citation(s) in RCA: 516] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
N-heterocyclic carbene ligands IMes (1), SIMes (2), IPr (3), SIPr (4), and ICy (5) react with Ni(CO)(4) to give the saturated tricarbonyl complexes Ni(CO)(3)(IMes) (8), Ni(CO)(3)(SIMes) (9), Ni(CO)(3)(IPr) (10), Ni(CO)(3)(SIPr) (11), and Ni(CO)(3)(ICy) (12), respectively. The electronic properties of these complexes have been compared to their phosphine analogues of general formula Ni(CO)(3)(PR(3)) by recording their nu(CO) stretching frequencies. While all of these NHCs are better donors than tertiary phosphines, the differences in donor properties between ligands 1-5 are surprisingly small. Novel, unsaturated Ni(CO)(2)(IAd) (13) and Ni(CO)(2)(I(t)()Bu) (14) compounds are obtained from the reaction of Ni(CO)(4) with IAd (6) and I(t)()Bu (7). Complexes 13 and 14 are highly active toward substitution of the NHC as well as the carbonyl ligands. This has allowed the determination of Ni-C(NHC) bond dissociation energies and the synthesis of various unsaturated Ni(0) and Ni(II) complexes. Computational studies on compounds 8-14 are in line with the experimental findings and show that IAd (6) and I(t)()Bu (7) are more bulky than IMes (1), SIMes (2), IPr (3), SIPr (4), and ICy (5). Furthermore, a method based on %V(bur) values has been developed for the direct comparison of steric requirements of NHCs and tertiary phosphines. Complexes 8-14, as well as NiCl(C(3)H(5))(I(t)()Bu) (16) and NiBr(C(3)H(5))(I(t)()Bu) (17), have been characterized by X-ray crystallography.
Collapse
Affiliation(s)
- Reto Dorta
- Department of Chemistry, University of New Orleans, New Orleans, Louisiana 70148, USA
| | | | | | | | | | | | | |
Collapse
|