51
|
Elkhayat E, Edrada R, Ebel R, Wray V, van Soest R, Wiryowidagdo S, Mohamed MH, Müller WEG, Proksch P. New luffariellolide derivatives from the Indonesian sponge Acanthodendrilla sp. JOURNAL OF NATURAL PRODUCTS 2004; 67:1809-1817. [PMID: 15568767 DOI: 10.1021/np040118j] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Investigation of the Indonesian sponge Acanthodendrilla sp. afforded five new luffariellolide-related sesterterpenes, acantholides A-E (1-5), in addition to luffariellolide and its 25-O-methyl and 25-O-ethyl derivatives. All structures were unambiguously established by 1D and 2D NMR and MS spectroscopy. Acantholide D and E are derivatives comprising the 1-acetylcyclopentan-5-ol moiety, which are new variants of the C(14)-C(20) segment for this type of linear sesterterpenes. Luffariellolide and its 25-O-methyl congener as well as acantholide E (5) were cytotoxic against the mouse lymphoma L5187Y cell line. Acantholide B (2), luffariellolide, and its 25-O-methyl congener were active against the Gram-positive bacteria Staphylococcus aureus and Bacillus subtilis, the Gram-negative bacterium Escherichia coli, the yeast Candida albicans, and the plant pathogenic fungus Cladosporium herbarum.
Collapse
Affiliation(s)
- Ehab Elkhayat
- Institut für Pharmazeutische Biologie, Heinrich-Heine-Universität, Universitätsstr 1, 40225 Düsseldorf, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
52
|
Cheung AK, Murelli R, Snapper ML. Total Syntheses of (+)- and (−)-Cacospongionolide B, Cacospongionolide E, and Related Analogues. Preliminary Study of Structural Features Required for Phospholipase A2 Inhibition. J Org Chem 2004; 69:5712-9. [PMID: 15307744 DOI: 10.1021/jo049285e] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The total syntheses of the antiinflammatory marine sponge metabolites (+)-cacospongionolide B and E are described. The pivotal steps in the synthetic route include a three-step sequence that couples the two main regions of the natural product, as well as generates the side chain dihydropyran ring. The activity of the synthetic analogues against bee venom phospholipase A2 suggests that the cacospongionolides have enantiospecific interactions with the enzyme that may be independent of the gamma-hydroxybutenolide moiety.
Collapse
Affiliation(s)
- Atwood K Cheung
- Department of Chemistry, Merkert Chemistry Center, Boston College, 2609 Beacon Street, Chestnut Hill, Massachusetts 02467, USA
| | | | | |
Collapse
|
53
|
Liao S, Collum DB. Lithium Diisopropylamide-Mediated Lithiations of Imines: Insights into Highly Structure-Dependent Rates and Selectivities. J Am Chem Soc 2003; 125:15114-27. [PMID: 14653747 DOI: 10.1021/ja030409z] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Lithium diisopropylamide-mediated lithiations of N-alkyl ketimines derived from cyclohexanones reveal that simple substitutions on the N-alkyl side chain and the 2-position of the cyclohexyl moiety afford a 60,000-fold range of rates. Detailed rate studies implicate monosolvated monomers at the rate-limiting transition structures in all instances. Comparisons of experimentally derived regioselectivities and rates, taken in conjunction with density functional theory computational studies, reveal a number of factors that influence reactivities including: (a) axial versus equatorial disposition of the proton on the cyclohexane ring, (b) syn versus anti orientation of the lithiation relative to the N-alkyl group, (c) the presence or absence of a potentially chelating methoxy moiety on the N-alkyl group, (d) the presence of a 2-methyl substituent at the geminal or distal alpha-carbon, and (e) branching in the N-alkyl group. The isolated contributions are not large, yet they display a strong and predictable additivity leading to a kinetic resolution of imines derived from racemic 2-methylcyclohexanone.
Collapse
Affiliation(s)
- Songping Liao
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
| | | |
Collapse
|
54
|
Ramírez A, Lobkovsky E, Collum DB. Hemilabile Ligands in Organolithium Chemistry: Substituent Effects on Lithium Ion Chelation. J Am Chem Soc 2003; 125:15376-87. [PMID: 14664582 DOI: 10.1021/ja030322d] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The lithium diisopropylamide-mediated 1,2-elimination of 1-bromocyclooctene to provide cyclooctyne is investigated using approximately 50 potentially hemilabile polyethers and amino ethers. Rate laws for selected ligands reveal chelated monomer-based pathways. The dependence of the rates on ligand structure shows that anticipated rate accelerations based on the gem-dimethyl effect are nonexistent and that substituents generally retard the reaction. With the aid of semiempirical and DFT computational studies, the factors influencing chelation are discussed. It seems that severe buttressing within chelates of the substitutionally rich ligands precludes a net stabilization of the chelates relative to nonchelated (eta(1)-solvated) forms. One ligand-MeOCH(2)CH(2)NMe(2)-appears to promote elimination uniquely by a higher-coordinate monomer-based pathway.
Collapse
Affiliation(s)
- Antonio Ramírez
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853-1301, USA
| | | | | |
Collapse
|
55
|
Zhao P, Collum DB. Ketone Enolization by Lithium Hexamethyldisilazide: Structural and Rate Studies of the Accelerating Effects of Trialkylamines. J Am Chem Soc 2003; 125:14411-24. [PMID: 14624589 DOI: 10.1021/ja030168v] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mechanistic studies of the enolization of 2-methylcyclohexanone mediated by lithium hexamethyldisilazide (LiHMDS; TMS2NLi) in toluene and toluene/amine mixtures are described. NMR spectroscopic studies of LiHMDS/ketone mixtures in toluene reveal the ketone-complexed cyclic dimer (TMS2NLi)2(ketone). Rate studies using in situ IR spectroscopy show the enolization proceeds via a dimer-based transition structure, [(TMS2NLi)2(ketone)]++. NMR spectroscopic studies of LiHMDS/ketone mixtures in the presence of relatively unhindered trialkylamines such as Me2NEt reveal the quantitative formation of cyclic dimers of general structure (TMS2NLi)2(R3N)(ketone). Rate studies trace a >200-fold rate acceleration to a dimer-based transition structure, [(TMS2NLi)2(R3N)(ketone)]++. Amines of intermediate steric demand, such as Et3N, are characterized by recalcitrant solvation, saturation kinetics, and exceptional (>3000-fold) accelerations traced to the aforementioned dimer-based pathway. Amines of high steric demand, such as i-Pr2NEt, do not observably solvate (TMS2NLi)2(ketone) but mediate enolization via [(TMS2NLi)2(R3N)(ketone)]++ with muted accelerations. The most highly hindered amines, such as i-Bu3N, do not influence the LiHMDS structure or the enolization rate. Overall, surprisingly complex dependencies of the enolization rates on the structures and concentrations of the amines derive from unexpectedly simple steric effects. The consequences of aggregation, mixed aggregation, and substrate-base precomplexation are discussed.
Collapse
Affiliation(s)
- Pinjing Zhao
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853-1301, USA
| | | |
Collapse
|
56
|
Hevia E, Kenley F, Kennedy A, Mulvey R, Rowlings R. Solvent‐Free and TMEDA‐Solvated Mixed Alkali Metal‐Magnesium Tris‐diisopropylamides. Eur J Inorg Chem 2003. [DOI: 10.1002/ejic.200300413] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Eva Hevia
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, U.K
| | - Fiona R. Kenley
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, U.K
| | - Alan R. Kennedy
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, U.K
| | - Robert E. Mulvey
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, U.K
| | - René B. Rowlings
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, U.K
| |
Collapse
|
57
|
|
58
|
Cheung AK, Snapper ML. Total Syntheses of (+)- and (−)-Cacospongionolide B: New Insight into Structural Requirements for Phospholipase A2 Inhibition. J Am Chem Soc 2002; 124:11584-5. [PMID: 12296709 DOI: 10.1021/ja026899x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The first total synthesis of the antiinflammatory marine sponge metabolite (+)-cacospongionolide B has been accomplished in 12 linear steps. The pivotal transformations include a three-step sequence coupling the two main regions of the natural product as well as generating the side chain dihydropyran ring. The activity of the synthetic analogues against bee venom phospholipase A(2) suggests that cacospongionolide B has an enantiospecific interaction with the enzyme that is independent of the gamma-hydroxybutenolide moiety.
Collapse
Affiliation(s)
- Atwood K Cheung
- Department of Chemistry, Merkert Chemistry Center, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467, USA
| | | |
Collapse
|
59
|
Cole ML, Junk PC, Louis LM. Synthesis and structural characterisation of some novel lithium and sodium N,N′-di(para-tolyl)formamidinate complexes. ACTA ACUST UNITED AC 2002. [DOI: 10.1039/b204047f] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
60
|
Carroll J, Jonsson EN, Ebel R, Hartman MS, Holman TR, Crews P. Probing sponge-derived terpenoids for human 15-lipoxygenase inhibitors. J Org Chem 2001; 66:6847-51. [PMID: 11597201 DOI: 10.1021/jo015784t] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A human 15-lipoxygenase (15-HLO) assay has been employed to discover new marine-sponge-derived bioactive compounds. Extracts from two different sponges, Jaspis splendens (order Choristida, family Jaspidae) and Suberea sp. (order Verongida, family Aplysinellidae), exhibited potent IC(50) values of 0.4 and 0.1 microg/mL, respectively. Both are sources of terpenoids, and the former is a known source of (+)-jasplakinolide (7), which is inactive as a 15-HLO inhibitor. The terpenoids included (+)-(5S,6S)-subersin (1, IC(50) > 100 microM), (-)-(5R,10R)-subersic acid (2, IC(50) = 15 microM), jaspaquinol (3, IC(50) = 0.3 microM), and (-)-jaspic acid (4, IC(50) = 1.4 microM). Structure elucidations and lipoxygenase activity studies of these compounds are reported.
Collapse
Affiliation(s)
- J Carroll
- Department of Chemistry and Biochemistry, Institute for Marine Sciences, University of California-Santa Cruz, California 95064, USA
| | | | | | | | | | | |
Collapse
|
61
|
Rutherford JL, Collum DB. Lithium diisopropylamide: oligomer structures at low ligand concentrations. J Am Chem Soc 2001; 123:199-202. [PMID: 11456504 DOI: 10.1021/ja003104i] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
One- and two-dimensional (6)Li and (15)N NMR spectroscopic studies of lithium diisopropylamide (LDA) solvated by substoichiometric concentrations of oxetane, THF, Et(2)O, and diisopropylamine are described. Partially solvated dimers and trimers are identified. Possible benefits of carrying out organolithium chemistry at low ligand concentrations are discussed.
Collapse
Affiliation(s)
- J L Rutherford
- Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301, USA
| | | |
Collapse
|
62
|
Galka CH, Trösch DJM, Rüdenauer I, Gade LH, Scowen I, McPartlin M. Synthesis and Structural Characterization of Metalated 1,8-Bis(silylamino)naphthalene Derivatives. Inorg Chem 2000. [DOI: 10.1021/ic000296+] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
63
|
Fontana A, Mollo E, Ortea J, Gavagnin M, Cimino G. Scalarane and homoscalarane compounds from the nudibranchs Glossodoris sedna and Glossodoris dalli: chemical and biological properties. JOURNAL OF NATURAL PRODUCTS 2000; 63:527-530. [PMID: 10785432 DOI: 10.1021/np990506z] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A series of homoscalarane and scalarane compounds (2-7) have been isolated from two distinct species of Pacific Glossodoris nudibranchs. The structure and elucidation of the relative stereochemistry of the new metabolites 2 and 3 were obtained by spectroscopic methods. Compound 2 was ichthyotoxic at 0.1 ppm against Gambusia affinis and showed moderate activity (IC(50) 18 microM) to inhibit mammalian phospholipase A(2).
Collapse
Affiliation(s)
- A Fontana
- Istituto per la Chimica di Molecole di Interesse Biologico (ICMIB)(1) del CNR, via Toiano 6, 80072 Arco Felice, Napoli, Italy.
| | | | | | | | | |
Collapse
|
64
|
Sun X, Collum DB. Lithium Diisopropylamide-Mediated Enolizations: Solvent-Independent Rates, Solvent-Dependent Mechanisms. J Am Chem Soc 2000. [DOI: 10.1021/ja992062z] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xiufeng Sun
- Contribution from the Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Contribution from the Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| |
Collapse
|
65
|
Ramírez A, Collum DB. Hemi-Labile Ligands in Organolithium Chemistry: Rate Studies of the LDA-Mediated α- and β-Metalations of Epoxides. J Am Chem Soc 1999. [DOI: 10.1021/ja992166+] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
66
|
van Vliet GLJ, de Kanter FJJ, Schakel M, Klumpp GW, Spek AL, Lutz M. X‐ray Crystal Structures and Some Solution Structures of Lithium Amides with Intramolecular Complexation of Lithium by Tertiary Amide Groups. Chemistry 1999. [DOI: 10.1002/(sici)1521-3765(19990301)5:3<1091::aid-chem1091>3.0.co;2-#] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- G. L. J. van Vliet
- Scheikundig Laboratorium, Vrije Universiteit Amsterdam, De Boelelaan 1083, NL‐1081 HV Amsterdam (The Netherlands), Fax: (+31) 20‐4447488
| | - F. J. J. de Kanter
- Scheikundig Laboratorium, Vrije Universiteit Amsterdam, De Boelelaan 1083, NL‐1081 HV Amsterdam (The Netherlands), Fax: (+31) 20‐4447488
| | - M. Schakel
- Scheikundig Laboratorium, Vrije Universiteit Amsterdam, De Boelelaan 1083, NL‐1081 HV Amsterdam (The Netherlands), Fax: (+31) 20‐4447488
| | - G. W. Klumpp
- Scheikundig Laboratorium, Vrije Universiteit Amsterdam, De Boelelaan 1083, NL‐1081 HV Amsterdam (The Netherlands), Fax: (+31) 20‐4447488
| | - A. L. Spek
- Bijvoet Center for Biomolecular Research, Universiteit Utrecht, Padualaan 8, NL‐3584 CH Utrecht (The Netherlands)
| | - M. Lutz
- Bijvoet Center for Biomolecular Research, Universiteit Utrecht, Padualaan 8, NL‐3584 CH Utrecht (The Netherlands)
| |
Collapse
|
67
|
Hitchcock PB, Lappert MF, Layh M. Ein 1-Aza-2-silacyclobut-3-en und ein Alkin aus [Li{Si(SiMe3)3}(thf)3] und dem Isocyanid 2,6-Me2C6H3NC. Angew Chem Int Ed Engl 1999. [DOI: 10.1002/(sici)1521-3757(19990215)111:4<562::aid-ange562>3.0.co;2-e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
68
|
|
69
|
De Rosa M, Giordano S, Scettri A, Sodano G, Soriente A, Pastor PG, Alcaraz MJ, Payá M. Synthesis and comparison of the antiinflammatory activity of manoalide and cacospongionolide B analogues. J Med Chem 1998; 41:3232-8. [PMID: 9703468 DOI: 10.1021/jm980027h] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
We have synthesized analogues of two naturally occurring antiinflammatory marine compounds, manoalide and cacospongionolide B, containing a pyranofuranone moiety which is considered the pharmacophoric group. The two compounds, and hence their analogues, differ in the presence or absence in the dihydropyran ring of an hemiacetal function which was considered essential to irreversibly inactivate phospholipase A2 (PLA2). The two series of compounds were tested for their inhibitory effects on secretory PLA2 belonging to the groups I, II, and III, and the activities were found to be similar in both series, irrespective of the presence or absence of the additional hemiacetal function. In addition, the PLA2 inhibitory activity increases with the increasing hydrophobic character of the side chain linked to the pyranofuranone moiety. The most active compounds, FCA and FMA, carry a farnesyl residue linked to the pyranofuranone substructure. The most potent PLA2 inhibitor, FMA, was tested in the mouse carrageenan paw edema at the oral dose of 10 mg/kg and showed an activity similar to the reference antiinflammatory drug, indomethacin.
Collapse
Affiliation(s)
- M De Rosa
- Dipartimento di Chimica, Università di Salerno, Via S. Allende, 84081 Baronissi (SA), Italy
| | | | | | | | | | | | | | | |
Collapse
|
70
|
Clegg W, Kleditzsch S, Mulvey RE, O'Shaughnessy P. Crystal structure of a heavier alkali metal diisopropylamide complex: a discrete (KN)2 ring dimer with TMEDA chelation and short intramolecular K⋯H(C) contacts. J Organomet Chem 1998. [DOI: 10.1016/s0022-328x(98)00391-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
71
|
Randazzo A, Debitus C, Minale L, García Pastor P, Alcaraz MJ, Payá M, Gomez-Paloma L. Petrosaspongiolides M-R: new potent and selective phospholipase A2 inhibitors from the New Caledonian marine sponge Petrosaspongia nigra. JOURNAL OF NATURAL PRODUCTS 1998; 61:571-5. [PMID: 9599251 DOI: 10.1021/np9704922] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Five new bioactive sesterterpenes (1-5) have been isolated from the New Caledonian marine sponge Petrosaspongia nigra Bergquist and named petrosaspongiolides M-R. Their chemical structures were determined from 1D and 2D NMR studies and MS data. All compounds inhibited different preparations of phospholipase A2 (PLA2) by irreversibly blocking these enzymes (particularly human synovial and bee venom, see Table 3), with IC50 values in the micromolar range. Interestingly, these compounds displayed a much lower activity (or no activity at all) toward porcine pancreas and Naja naja venom PLA2 enzymes. The most potent compound, 1 (IC50 1.6 and 0.6 microM for human synovial and bee venom PLA2 enzymes, respectively), was slightly more active than manoalide (6) (IC50 3.9 and 7.5 microM) under our experimental conditions. Compound 3 is more selective, inhibiting human synovial PLA2 to a greater extent than bee venom PLA2.
Collapse
Affiliation(s)
- A Randazzo
- Dipartimento di Chimica delle Sostanze Naturali, Università degli Studi di Napoli "Federico II", via D. Montesano 49, 80131 Napoli, Italy
| | | | | | | | | | | | | |
Collapse
|
72
|
Remenar JF, Collum DB. Structure and Reactivity of Lithium Diisopropylamide Solvated by Polyamines: Evidence of Monomer- and Dimer-Based Dehydrohalogenations. J Am Chem Soc 1998. [DOI: 10.1021/ja9741279] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Julius F. Remenar
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| |
Collapse
|
73
|
The effect of (poly)amine ligands on the solution structure of [6Li]-α-(phenylthio)benzyllithium in tetrahydrofuran: A 1H,6Li-HOESY NMR study1Dedicated to Professor Ken Wade on the occasion of his 65th birthday.1. J Organomet Chem 1998. [DOI: 10.1016/s0022-328x(97)00239-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
74
|
E. Mulvey R. Synthetic and structural developments in hetero-s-block-metal chemistry: new ring-laddering, ring-stacking and other architectures. Chem Soc Rev 1998. [DOI: 10.1039/a827339z] [Citation(s) in RCA: 162] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
75
|
Henderson KW, Dorigo AE, Liu QY, Williard PG. Effect of Polydentate Donor Molecules on Lithium Hexamethyldisilazide Aggregation: An X-ray Crystallographic and a Combination Semiempirical PM3/Single Point ab Initio Theoretical Study. J Am Chem Soc 1997. [DOI: 10.1021/ja971920t] [Citation(s) in RCA: 70] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kenneth W. Henderson
- Contribution from the Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, UK, and Department of Chemistry, Brown University, Providence, Rhode Island 02912
| | - Andrea E. Dorigo
- Contribution from the Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, UK, and Department of Chemistry, Brown University, Providence, Rhode Island 02912
| | - Qi-Yong Liu
- Contribution from the Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, UK, and Department of Chemistry, Brown University, Providence, Rhode Island 02912
| | - Paul G. Williard
- Contribution from the Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, G1 1XL, UK, and Department of Chemistry, Brown University, Providence, Rhode Island 02912
| |
Collapse
|
76
|
Poetschke N, Nieger M, Khan MA, Niecke E, Ashby MT. Synthesis and Crystal Structures of Lithium Salts of New Iminophosphide/Phosphinoamide Anions. Inorg Chem 1997. [DOI: 10.1021/ic9700720] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Norbert Poetschke
- Anorganisch Chemisches Institut der Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany, and Department of Chemistry and Biochemistry, The University of Oklahoma, Norman, Oklahoma 73019
| | - Martin Nieger
- Anorganisch Chemisches Institut der Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany, and Department of Chemistry and Biochemistry, The University of Oklahoma, Norman, Oklahoma 73019
| | - Masood A. Khan
- Anorganisch Chemisches Institut der Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany, and Department of Chemistry and Biochemistry, The University of Oklahoma, Norman, Oklahoma 73019
| | - Edgar Niecke
- Anorganisch Chemisches Institut der Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany, and Department of Chemistry and Biochemistry, The University of Oklahoma, Norman, Oklahoma 73019
| | - Michael T. Ashby
- Anorganisch Chemisches Institut der Universität Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany, and Department of Chemistry and Biochemistry, The University of Oklahoma, Norman, Oklahoma 73019
| |
Collapse
|
77
|
Remenar JF, Lucht BL, Kruglyak D, Romesberg FE, James H. Gilchirst, and, Collum DB. Lithium 2,2,6,6-Tetramethylpiperidide and Lithium 2,2,4,6,6-Pentamethylpiperidide: Influence of TMEDA and Related Chelating Ligands on the Solution Structures. Characterization of Higher Cyclic Oligomers, Cyclic Dimers, Open Dimers, and Monomers. J Org Chem 1997. [DOI: 10.1021/jo970520l] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Julius F. Remenar
- Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Brett L. Lucht
- Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Dmitriy Kruglyak
- Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Floyd E. Romesberg
- Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | | | - David B. Collum
- Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| |
Collapse
|
78
|
Fryzuk MD, Hoffman V, Kickham JE, Rettig SJ, Gambarotta S. Synthesis and Structure of a New Lithium Amide Ligand Precursor: A Tridentate Nitrogen-Based Donor Set of the Formula N(SiMe(2)CH(2)NMe(2))(2). Synthesis and Structure of the Group 4 Amides MCl(3)[N(SiMe(2)CH(2)NMe(2))(2)] (M = Ti, Zr, Hf). Inorg Chem 1997; 36:3480-3484. [PMID: 11670025 DOI: 10.1021/ic970168u] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The new lithium amide LiN(SiMe(2)CH(2)NMe(2))(2) was prepared by reaction of NH(3) with the corresponding silylamine Me(2)NSiMe(2)CH(2)NMe(2) followed by addition of butyllithium. This lithium derivative exists as a dimer in the solid state wherein the two lithium ions are bridged by the two amido units with the amine arms of each unit bonded to opposite lithium centers in an overall pseudo D(2) structure; however, in solution, a fluxional process serves to interconvert the enantiomeric forms of the dimer unit. The coordination chemistry of the lithium amide dimer has been investigated; reaction with a series of group 4 starting halides, MCl(4), leads to the corresponding complexes MCl(3)[N(SiMe(2)CH(2)NMe(2))(2)], where M = Ti, Zr, and Hf. The structures of these starting trihalides in solution and in the solid state are presented.
Collapse
Affiliation(s)
- Michael D. Fryzuk
- Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario, Canada K1N 6N5
| | | | | | | | | |
Collapse
|
79
|
Remenar JF, Collum DB. Chelation-Based Stabilization of the Transition Structure in a Lithium Diisopropylamide Mediated Dehydrobromination: Avoiding the “Universal Ground State” Assumption. J Am Chem Soc 1997. [DOI: 10.1021/ja970030a] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Julius F. Remenar
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| |
Collapse
|
80
|
Remenar JF, Lucht BL, Collum DB. Lithium Diisopropylamide Solvated by Monodentate and Bidentate Ligands: Solution Structures and Ligand Binding Constants. J Am Chem Soc 1997. [DOI: 10.1021/ja970029b] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Julius F. Remenar
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Brett L. Lucht
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| |
Collapse
|
81
|
Sun X, Kenkre SL, Remenar JF, Gilchrist JH, Collum DB. Mechanism of Lithium Diisopropylamide-Mediated Ester Deprotonation: The Role of Disolvated Monomers. J Am Chem Soc 1997. [DOI: 10.1021/ja970406k] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Xiufeng Sun
- Department of Chemistry, Baker Laboratory Cornell University, Ithaca, New York 14853-1301
| | - Sarita L. Kenkre
- Department of Chemistry, Baker Laboratory Cornell University, Ithaca, New York 14853-1301
| | - Julius F. Remenar
- Department of Chemistry, Baker Laboratory Cornell University, Ithaca, New York 14853-1301
| | - James H. Gilchrist
- Department of Chemistry, Baker Laboratory Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Department of Chemistry, Baker Laboratory Cornell University, Ithaca, New York 14853-1301
| |
Collapse
|
82
|
Clegg W, Greer JC, Hayes JM, Mair FS, Nolan PM, O'Neil PA. Mixed aggregation between lithium diisopropylamide and lithium chloride: NMR, solid-state structure and ab initio calculations. Inorganica Chim Acta 1997. [DOI: 10.1016/s0020-1693(96)05493-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
83
|
Rychnovsky SD, Swenson SS. Alkylation and Reductive Decyanation of 4-Cyano-2,2-dimethyl-1,3-dioxanes (Cyanohydrin Acetonides). J Org Chem 1997. [DOI: 10.1021/jo961826f] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Scott D. Rychnovsky
- Department of Chemistry, University of California, Irvine, California, 92697-2025
| | - Sonja S. Swenson
- Department of Chemistry, University of California, Irvine, California, 92697-2025
| |
Collapse
|
84
|
Fryzuk MD, Giesbrecht GR, Rettig SJ. Synthesis, Characterization, and Solution Dynamics of Alkali-Metal Chloride, Aluminate, and Borate Adducts of the Tridentate Amido Diphosphine Ligand Precursor LiN(SiMe2CH2PPri2)2. Organometallics 1997. [DOI: 10.1021/om960638c] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Michael D. Fryzuk
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1
| | - Garth R. Giesbrecht
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1
| | - Steven J. Rettig
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, British Columbia, Canada V6T 1Z1
| |
Collapse
|
85
|
Lucht BL, Bernstein MP, Remenar JF, Collum DB. Polydentate Amine and Ether Solvates of Lithium Hexamethyldisilazide (LiHMDS): Relationship of Ligand Structure, Relative Solvation Energy, and Aggregation State. J Am Chem Soc 1996. [DOI: 10.1021/ja9618199] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Brett L. Lucht
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Max P. Bernstein
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - Julius F. Remenar
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| | - David B. Collum
- Contribution from the Department of Chemistry, Baker Laboratory, Cornell University, Ithaca, New York 14853-1301
| |
Collapse
|
86
|
Andrews PC, Barnett ND, Mulvey RE, Clegg W, O'Neil PA, Barr D, Cowton L, Dawson AJ, Wakefield BJ. X-ray crystallographic studies and comparative reactivity studies of a sodium diisopropylamide (NDA) complex and related hindered amides. J Organomet Chem 1996. [DOI: 10.1016/0022-328x(96)06203-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
87
|
Koch R, Wiedel B, Anders E. Theoretical Study of the Deprotonation of Nitriles, RCH2CN: Ab Initio and PM3 Calculations of Intermediate Aggregates and Transition States. J Org Chem 1996. [DOI: 10.1021/jo9519470] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rainer Koch
- Institut für Organische Chemie und Makromolekulare Chemie der Universität Jena, Humboldtstrasse 10, D-07743 Jena, Germany
| | - Bernd Wiedel
- Institut für Organische Chemie und Makromolekulare Chemie der Universität Jena, Humboldtstrasse 10, D-07743 Jena, Germany
| | - Ernst Anders
- Institut für Organische Chemie und Makromolekulare Chemie der Universität Jena, Humboldtstrasse 10, D-07743 Jena, Germany
| |
Collapse
|
88
|
Kremer T, Harder S, Junge M, Schleyer PVR. Mixed Aggregates of Alkali Metal Compounds: Structure and Stability of “Superbase” Models. Organometallics 1996. [DOI: 10.1021/om950720s] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Thomas Kremer
- Institut für Organische Chemie der Friedrich Alexander Universität Erlangen-Nürnberg, Henkestrasse 42, D-91054 Erlangen, Germany
| | - Sjoerd Harder
- Institut für Organische Chemie der Friedrich Alexander Universität Erlangen-Nürnberg, Henkestrasse 42, D-91054 Erlangen, Germany
| | - Michael Junge
- Institut für Organische Chemie der Friedrich Alexander Universität Erlangen-Nürnberg, Henkestrasse 42, D-91054 Erlangen, Germany
| | - Paul von Ragué Schleyer
- Institut für Organische Chemie der Friedrich Alexander Universität Erlangen-Nürnberg, Henkestrasse 42, D-91054 Erlangen, Germany
| |
Collapse
|
89
|
Knop O, Bakshi PK. Crystal chemistry of tetraradial species. Part 7. Lithium tetrakis(1-imidazolyl)-borate solvate, Liiv[Liiv(H2O)(MeOH)]-[B(C3H3N2)4]2•MeOH, a 3-dimensional polymer; with observations on the geometry of imidazole rings. CAN J CHEM 1995. [DOI: 10.1139/v95-023] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The title compound is a 3-dimensional polymer with a completely ordered triclinic structure [Formula: see text] a = 12.380(2) Å, b = 14.434(2) Å, c = 9.683(3) Å, α = 90.36(2)°, β = 105.44(2)°, γ = 90.75(2)°, Z = 2). Every B atom is tetrahedrally coordinated by N(1) atoms of the imidazole rings, every Li(1) atom is tetrahedrally coordinated by N(3) atoms, and every Li(2) atom is coordinated by two N(3) and two oxygen atoms, one from the H2O molecule and one from a MeOH molecule. The imidazole rings connected by the B—N(1) and Li—N(3) bonds thus generate a 3-dimensional covalent polymeric network. The MeOH molecules of coordination are hydrogen-bonded to unengaged N(3) atoms, thereby supplementing the covalent bonding system. The H2O molecules are hydrogen-bonded to the MeOH molecules of solvation to form centrosymmetric [Ow … OMeOH]2 rings, which in turn are connected to the covalent network by OMeOH—H … N(3) bonds to the remaining unengaged N(3) atoms. Every atom in the structure except the H(C) hydrogens is thus involved in the 3-dimensional bond system. The excellent consistency of the bond lengths and endocyclic bond angles [Formula: see text] in the eight imidazole rings of the title compound has provided an opportunity for investigating the effect of substitution on the geometry of the imidazole ring in a sample of 17 substituted imidazoles. While the bond lengths have been found at most weakly correlated, the multilinear correlations of the [Formula: see text] in this sample are highly significant. Among the substituents the NO2, group is the most ipso- [Formula: see text] -expanding and the anionic B (in the title compound) the most ipso- [Formula: see text] -contracting. Protonation or deprotonation at the N atoms affect the ipso C—N—C angles considerably. Limited comparisons are drawn with the results of the classical investigations by Domenicano et al. on the effect of substitution on the geometry of the benzene ring. Keywords: hydrogen bond, imidazole, lithium compounds, polymers, tetrahedral boron ions.
Collapse
|
90
|
|
91
|
Westerhausen M, Schwarz W. Tris(trimethylsilyl)silylamin und seine lithiierten und silylierten Derivate ? Kristallstruktur des dimeren Lithium-trimethylsilyl-[tris(trimethylsilyl)silyl]amids. Z Anorg Allg Chem 1993. [DOI: 10.1002/zaac.19936190616] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|