1
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Efficient Synthesis of 1 H-Benzo[4,5]imidazo[1,2- c][1,3]oxazin-1-one Derivatives Using Ag 2CO 3/TFA-Catalyzed 6- endo-dig Cyclization: Reaction Scope and Mechanistic Study. Molecules 2023; 28:molecules28052403. [PMID: 36903655 PMCID: PMC10005794 DOI: 10.3390/molecules28052403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 02/27/2023] [Accepted: 02/28/2023] [Indexed: 03/09/2023] Open
Abstract
A small library of 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-one derivatives was prepared in good to excellent yields, involving a Ag2CO3/TFA-catalyzed intramolecular oxacyclization of N-Boc-2-alkynylbenzimidazole substrates. In all experiments, the 6-endo-dig cyclization was exclusively achieved since the possible 5-exo-dig heterocycle was not observed, indicating the high regioselectivity of this process. The scope and limitations of the silver catalyzed 6-endo-dig cyclization of N-Boc-2-alkynylbenzimidazoles as substrates, bearing various substituents, were investigated. While ZnCl2 has shown limits for alkynes with an aromatic substituent, Ag2CO3/TFA demonstrated its effectiveness and compatibility regardless of the nature of the starting alkyne (aliphatic, aromatic or heteroaromatic), providing a practical regioselective access to structurally diverse 1H-benzo[4,5]imidazo[1,2-c][1,3]oxazin-1-ones in good yields. Moreover, the rationalization of oxacyclization selectivity in favor of 6-endo-dig over 5-exo-dig was explained by a complementary computational study.
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2
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Saraswat M, Ravi S, Shamasundar KR, Venkataramani S. Photochemistry of 3,6-Didehydropyridazine Biradical─An Untraceable Para Benzyne Analogue. J Phys Chem A 2022; 126:557-567. [PMID: 35049300 DOI: 10.1021/acs.jpca.1c09317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report matrix isolation infrared spectroscopic studies to characterize 3,6-didehydropyridazine 6, a heterocyclic analogue of para benzyne, combined with computations. In this regard, we have utilized 3,6-diiodopyridazine 11 as a photolytic precursor. The experiments toward the generation of the biradical are carried out in argon and nitrogen matrices at 4 K. Instead of the elusive biradical, we have observed a ring-opening product maleonitrile (Z)-7 upon irradiation at 254 nm. In contrast, prolonged irradiation at 254 nm leads only to Z-E isomerization, forming fumaronitrile (E)-7. The mechanistic aspects of ring-opening, product selectivity, and Z-E photoisomerization steps have been investigated in detail using high-level ab initio computations. These studies have found that 3,6-didehydropyridazine 6 is an untraceable intermediate, and the ring-opening step leading to maleonitrile is barrierless. In addition, we have proposed the involvement of the S1 (π-π*) state via conical intersection in the Z-E photoisomerization of maleonitrile.
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Affiliation(s)
- Mayank Saraswat
- Department of Chemical Sciences, Indian Institute of Science Education and Research, Mohali Knowledge City, Sector 81, SAS Nagar, Manauli 140306, India
| | | | - K R Shamasundar
- Department of Chemical Sciences, Indian Institute of Science Education and Research, Mohali Knowledge City, Sector 81, SAS Nagar, Manauli 140306, India
| | - Sugumar Venkataramani
- Department of Chemical Sciences, Indian Institute of Science Education and Research, Mohali Knowledge City, Sector 81, SAS Nagar, Manauli 140306, India
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3
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Wipf P, P. Montoya A, G. LaPorte M. Synthesis of Benzo[d]pyrrolo[1,2-a]imidazoles by Iminocyclopropane Rearrangement of C-Cyclopropylbenzimidazoles. HETEROCYCLES 2022. [DOI: 10.3987/com-22-s(r)22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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4
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Affiliation(s)
- Ya‐Feng Si
- School of Biology Zhengzhou University Zhengzhou 450001 People's Republic of China
- Green Catalysis Center, College of Chemistry Zhengzhou University Zhengzhou 450001 People's Republic of China
| | - Qi‐Yan Lv
- School of Biology Zhengzhou University Zhengzhou 450001 People's Republic of China
- Green Catalysis Center, College of Chemistry Zhengzhou University Zhengzhou 450001 People's Republic of China
| | - Bing Yu
- Green Catalysis Center, College of Chemistry Zhengzhou University Zhengzhou 450001 People's Republic of China
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5
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Zhao L, Yang H, Li R, Tao Y, Guo XF, Anderson EA, Whiting A, Wu N. Synthesis of Sulfonamide-Based Ynamides and Ynamines in Water. J Org Chem 2021; 86:1938-1947. [PMID: 33356269 DOI: 10.1021/acs.joc.0c02326] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Ynamides, though relatively more stable than ynamines, are still moisture-sensitive and prone to hydration especially under acidic and heating conditions. Here we report an environmentally benign, robust protocol to synthesize sulfonamide-based ynamides and arylynamines via Sonogashira coupling reactions in water, using a readily available quaternary ammonium salt as the surfactant.
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Affiliation(s)
- Lei Zhao
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Science, Guangxi Normal University, Guilin, Guangxi 541004, China
| | - Hongyi Yang
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Science, Guangxi Normal University, Guilin, Guangxi 541004, China
| | - Ruikun Li
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Science, Guangxi Normal University, Guilin, Guangxi 541004, China
| | - Ye Tao
- State Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources, School of Chemistry and Pharmaceutical Science, Guangxi Normal University, Guilin, Guangxi 541004, China
| | - Xiao-Feng Guo
- College of Biomedical Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024, China
| | - Edward A Anderson
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Andrew Whiting
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K
| | - Na Wu
- School of Chemistry and Bioscience, University of Bradford, Bradford, West Yorkshire BD7 1DP, U.K
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6
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Hua-Feng H, Yang Y, Yongwen J, Weiliang B. Synthesis of Diynes from 1-(2,2-Dibromovinyl)-2-(Phenylethynyl)Benzene and Imidazole/Benzimidazole Via a Cui/Pd(Oac)2 Catalysed Cascade Reaction. JOURNAL OF CHEMICAL RESEARCH 2019. [DOI: 10.3184/174751914x14019525018744] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- He Hua-Feng
- Tea Research Institute, Chinese Academy of Agricultural Sciences
- Key Laboratory of Tea Biology and Resources Utilization, Ministry of Agriculture
- National Engineering Technology Research Center of Tea Industry
| | - Ye Yang
- Tea Research Institute, Chinese Academy of Agricultural Sciences
- Key Laboratory of Tea Biology and Resources Utilization, Ministry of Agriculture
- National Engineering Technology Research Center of Tea Industry
| | - Jiang Yongwen
- Tea Research Institute, Chinese Academy of Agricultural Sciences
- Key Laboratory of Tea Biology and Resources Utilization, Ministry of Agriculture
- National Engineering Technology Research Center of Tea Industry
| | - Bao Weiliang
- Department of Chemistry, Zhejiang University, Hangzhou, Zhejiang 310008, P.R. China
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7
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Reinus B, Kerwin SM. Preparation and Utility of N-Alkynyl Azoles in Synthesis. Molecules 2019; 24:E422. [PMID: 30682796 PMCID: PMC6384649 DOI: 10.3390/molecules24030422] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 01/16/2019] [Accepted: 01/22/2019] [Indexed: 12/05/2022] Open
Abstract
Heteroatom-substituted alkynes have attracted a significant amount of interest in the synthetic community due to the polarized nature of these alkynes and their utility in a wide range of reactions. One specific class of heteroatom-substituted alkynes combines this utility with the presence of an azole moiety. These N-alkynyl azoles have been known for nearly 50 years, but recently there has been a tremendous increase in the number of reports detailing the synthesis and utility of this class of compound. While much of the chemistry of N-alkynyl azoles mirrors that of the more extensively studied N-alkynyl amides (ynamides), there are notable exceptions. In addition, as azoles are extremely common in natural products and pharmaceuticals, these N-alkynyl azoles have high potential for accessing biologically important compounds. In this review, the literature reports of N-alkynyl azole synthesis, reactions, and uses have been assembled. Collectively, these reports demonstrate the growth in this area and the promise of exploiting N-alkynyl azoles in synthesis.
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Affiliation(s)
- Brandon Reinus
- Department of Chemistry, University of Texas at Austin, Austin, TX 78712, USA.
| | - Sean M Kerwin
- Department of Chemistry & Biochemistry, Texas State University, San Marcos, TX 78666, USA.
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8
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Han WJ, Wang YR, Zhang JW, Chen F, Zhou B, Han B. Cu-Catalyzed Oxyalkynylation and Aminoalkynylation of Unactivated Alkenes: Synthesis of Alkynyl-Featured Isoxazolines and Cyclic Nitrones. Org Lett 2018; 20:2960-2963. [PMID: 29701474 DOI: 10.1021/acs.orglett.8b01004] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A convenient and efficient vicinal oxyalkynylation/aminoalkynylation of internal unactivated alkenes is achieved by means of a Cu-catalyzed radical cascade reaction of unsaturated ketoximes with ethynylbenziodoxolone (EBX) reagents. This protocol enables the synthesis of structurally valuable isoxazolines or cyclic nitrones and the introduction of an important alkyne group in a single operation. The reaction is characterized by a broad substrate scope for both unsaturated ketoximes and alkynylation reagents and a low catalyst loading.
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Affiliation(s)
- Wen-Jun Han
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , 730000 , P. R. China
| | - Yuan-Rui Wang
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , 730000 , P. R. China
| | - Jian-Wu Zhang
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , 730000 , P. R. China
| | - Fei Chen
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , 730000 , P. R. China
| | - Bo Zhou
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , 730000 , P. R. China
| | - Bing Han
- State Key Laboratory of Applied Organic Chemistry, College of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou , 730000 , P. R. China
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9
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Umezono S, Okuno T. Systematic study of intermolecular C–X⋯O S (X = Cl, Br, I) halogen bonds in (E)-10-(1,2-dihalovinyl)-10H-phenothiazine 5,5-dioxides. J Mol Struct 2017. [DOI: 10.1016/j.molstruc.2017.06.135] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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10
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Das R, Hepp A, Daniliuc CG, Hahn FE. Synthesis of Complexes with Protic NH,NH-NHC Ligands via Oxidative Addition of 2-Halogenoazoles to Zero-Valent Transition Metals. Organometallics 2014. [DOI: 10.1021/om501120u] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Affiliation(s)
- Rajorshi Das
- Institut
für Anorganische und Analytische Chemie and NRW Graduate School
of Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse
30, D-48149 Münster, Germany
| | - Alexander Hepp
- Institut
für Anorganische und Analytische Chemie and NRW Graduate School
of Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse
30, D-48149 Münster, Germany
| | - Constantin G. Daniliuc
- Organisch-Chemisches
Institut, Westfälische Wilhelms-Universität Münster, Corrensstrasse 40, D-48149 Münster, Germany
| | - F. Ekkehardt Hahn
- Institut
für Anorganische und Analytische Chemie and NRW Graduate School
of Chemistry, Westfälische Wilhelms-Universität Münster, Corrensstrasse
30, D-48149 Münster, Germany
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11
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Kiruthika SE, Nandakumar A, Perumal PT. Synthesis of Pyrrolo-/Indolo[1,2-a]quinolines and Naphtho[2,1-b]thiophenes from gem-Dibromovinyls and Sulphonamides. Org Lett 2014; 16:4424-7. [DOI: 10.1021/ol5019085] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Selvarangam E. Kiruthika
- Organic Chemistry Division, CSIR-Central Leather Research Institute, Adyar,
Chennai-600020, Tamilnadu, India
| | - Avanashiappan Nandakumar
- Organic Chemistry Division, CSIR-Central Leather Research Institute, Adyar,
Chennai-600020, Tamilnadu, India
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12
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Affiliation(s)
- Robert S. Sheridan
- Department of Chemistry, University of Nevada, Reno, Nevada 89557, United States
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13
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Mohamed RK, Peterson PW, Alabugin IV. Concerted Reactions That Produce Diradicals and Zwitterions: Electronic, Steric, Conformational, and Kinetic Control of Cycloaromatization Processes. Chem Rev 2013; 113:7089-129. [DOI: 10.1021/cr4000682] [Citation(s) in RCA: 166] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Rana K. Mohamed
- Department of Chemistry
and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390,
United States
| | - Paul W. Peterson
- Department of Chemistry
and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390,
United States
| | - Igor V. Alabugin
- Department of Chemistry
and Biochemistry, Florida State University, Tallahassee, Florida 32306-4390,
United States
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14
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How to Lose a Bond in Two Ways ― The Diradical/Zwitterion Dichotomy in Cycloaromatization Reactions. European J Org Chem 2013. [DOI: 10.1002/ejoc.201201656] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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15
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Aleksandrova EV, Kravchenko AN, Kochergin PM. Properties of haloimidazoles (review). Chem Heterocycl Compd (N Y) 2011. [DOI: 10.1007/s10593-011-0754-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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16
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Laroche C, Li J, Kerwin SM. Cytotoxic 1,2-dialkynylimidazole-based aza-enediynes: aza-Bergman rearrangement rates do not predict cytotoxicity. J Med Chem 2011; 54:5059-69. [PMID: 21667990 DOI: 10.1021/jm200289j] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A new class of potential antitumor agents inspired by the enediyne antitumor antibiotics has been synthesized: the 1,2-dialkynylimidazoles. The aza-Bergman rearrangement of these 1,2-dialkynylimidazoles has been investigated theoretically at the B3LYP/6-31G(d,p) level and experimentally by measuring the kinetics of rearrangement in 1,4-cyclohexadiene. There is a good correlation between the theoretical and experimental results; subtle substituent effects on the initial aza-Bergman cyclization barrier predicted by theory are confirmed by experiment. Yet, despite the ability of these 1,2-dialkynylimidazoles to undergo Bergman rearrangement to diradical/carbene intermediates under relatively mild conditions, there is no correlation between the rate of Bergman cyclization and cytotoxicity to A459 cells. In addition, cytotoxic 1,2-dialkynylimidazoles do not cause nicking of supercoiled plasmid DNA or cleavage of bovine serum albumin. An alternative mechanism for cytotoxicity involving the unexpected selective thiol addition to the N-ethynyl group of certain 1,2-dialkynylimidazoles is proposed.
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Affiliation(s)
- Christophe Laroche
- Division of Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Texas 78712, USA
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17
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18
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Peddibhotla S, Shi R, Khan P, Smith LH, Mangravita-Novo A, Vicchiarelli M, Su Y, Okolotowicz KJ, Cashman JR, Reed JC, Roth GP. Inhibition of protein kinase C-driven nuclear factor-kappaB activation: synthesis, structure-activity relationship, and pharmacological profiling of pathway specific benzimidazole probe molecules. J Med Chem 2010; 53:4793-7. [PMID: 20481485 PMCID: PMC2887059 DOI: 10.1021/jm1000248] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
A unique series of biologically active chemical probes that selectively inhibit NF-kappaB activation induced by protein kinase C (PKC) pathway activators have been identified through a cell-based phenotypic reporter gene assay. These 2-aminobenzimidazoles represent initial chemical tools to be used in gaining further understanding on the cellular mechanisms driven by B and T cell antigen receptors. Starting from the founding member of this chemical series 1a (notated in PubChem as CID-2858522), we report the chemical synthesis, SAR studies, and pharmacological profiling of this pathway-selective inhibitor of NF-kappaB activation.
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Affiliation(s)
- Satyamaheshwar Peddibhotla
- Conrad Prebys Center for Chemical Genomics, Sanford-Burnham Medical Research Institute, 6400 Sanger Road, Orlando, Florida 32827, USA
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19
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Bellina F, Rossi R. Regioselective Functionalization of the Imidazole Ring via Transition Metal-Catalyzed CN and CC Bond Forming Reactions. Adv Synth Catal 2010. [DOI: 10.1002/adsc.201000144] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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20
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Evano G, Coste A, Jouvin K. Ynamides: Versatile Tools in Organic Synthesis. Angew Chem Int Ed Engl 2010; 49:2840-59. [DOI: 10.1002/anie.200905817] [Citation(s) in RCA: 672] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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21
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Evano G, Coste A, Jouvin K. Inamide: vielseitige Bausteine für die organische Synthese. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.200905817] [Citation(s) in RCA: 213] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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22
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Li Y, Jin J, Qian W, Bao W. An efficient and convenient Cu(OAc)2/air mediated oxidative coupling of azoles via C–H activation. Org Biomol Chem 2010; 8:326-30. [DOI: 10.1039/b919396k] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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23
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Laroche C, Li J, Gonzales C, David WM, Kerwin SM. Cyclization kinetics and biological evaluation of an anticancer 1,2-dialkynylimidazole. Org Biomol Chem 2010; 8:1535-9. [DOI: 10.1039/b925261d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Li J, Kaoud TS, Laroche C, Dalby KN, Kerwin SM. Synthesis and biological evaluation of p38alpha kinase-targeting dialkynylimidazoles. Bioorg Med Chem Lett 2009; 19:6293-7. [PMID: 19822424 DOI: 10.1016/j.bmcl.2009.09.094] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2009] [Revised: 09/22/2009] [Accepted: 09/24/2009] [Indexed: 12/22/2022]
Abstract
Based on the mild, thermal rearrangement of 1,2-dialkynylimidazoles to reactive carbene or diradical intermediates, a series of 1,2-dialkynylimidazoles were designed as potential irreversible p38 MAP kinase alpha-isoform (p38alpha) inhibitors. The synthesis of these dialkynylimidazoles and their kinase inhibition activity is reported. The 1-ethynyl-substituted dialkynylimidazole 14 is a potent (IC(50)=200 nM) and selective inhibitor of p38alpha. Moreover, compound 14 covalently modifies p38alpha as determined by ESI-MS after 12h incubation at 37 degrees C. The unique kinase inhibition, covalent kinase adduct formation, and minimal CYP450 2D6 inhibition by compound 14 demonstrate that dialkynylimidazoles are a new, promising class of p38alpha inhibitors.
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Affiliation(s)
- Jing Li
- Division of Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, TX, USA
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25
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Laroche C, Kerwin SM. Lithiation and functionalization of 1-alkynylimidazoles at the 2-position. Tetrahedron Lett 2009. [DOI: 10.1016/j.tetlet.2009.06.133] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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26
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Kerhervé J, Botuha C, Dubois J. New asymmetric synthesis of protein farnesyltransferase inhibitors via palladium-catalyzed cross-coupling reactions of 2-iodo-imidazoles. Org Biomol Chem 2009; 7:2214-22. [DOI: 10.1039/b902601k] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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27
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Laroche C, Li J, Freyer MW, Kerwin SM. Coupling Reactions of Bromoalkynes with Imidazoles Mediated by Copper Salts: Synthesis of Novel N-Alkynylimidazoles. J Org Chem 2008; 73:6462-5. [DOI: 10.1021/jo801118q] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Christophe Laroche
- Division of Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78712
| | - Jing Li
- Division of Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78712
| | - Matthew W. Freyer
- Division of Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78712
| | - Sean M. Kerwin
- Division of Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78712
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Schnürch M, Flasik R, Khan AF, Spina M, Mihovilovic MD, Stanetty P. Cross‐Coupling Reactions on Azoles with Two and More Heteroatoms. European J Org Chem 2006. [DOI: 10.1002/ejoc.200600089] [Citation(s) in RCA: 252] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Michael Schnürch
- Vienna University of Technology, Institute of Applied Synthetic Chemistry, Getreidemarkt 9/163‐OC, 1060 Vienna, Austria, Fax: +43‐1‐58801‐15499
| | - Radoslav Flasik
- Vienna University of Technology, Institute of Applied Synthetic Chemistry, Getreidemarkt 9/163‐OC, 1060 Vienna, Austria, Fax: +43‐1‐58801‐15499
| | - Ather Farooq Khan
- Vienna University of Technology, Institute of Applied Synthetic Chemistry, Getreidemarkt 9/163‐OC, 1060 Vienna, Austria, Fax: +43‐1‐58801‐15499
| | - Markus Spina
- Vienna University of Technology, Institute of Applied Synthetic Chemistry, Getreidemarkt 9/163‐OC, 1060 Vienna, Austria, Fax: +43‐1‐58801‐15499
| | - Marko D. Mihovilovic
- Vienna University of Technology, Institute of Applied Synthetic Chemistry, Getreidemarkt 9/163‐OC, 1060 Vienna, Austria, Fax: +43‐1‐58801‐15499
| | - Peter Stanetty
- Vienna University of Technology, Institute of Applied Synthetic Chemistry, Getreidemarkt 9/163‐OC, 1060 Vienna, Austria, Fax: +43‐1‐58801‐15499
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29
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Feng L, Zhang A, Kerwin SM. Enediynes from Aza-Enediynes: C,N-Dialkynyl Imines Undergo Both Aza-Bergman Rearrangement and Conversion to Enediynes and Fumaronitriles. Org Lett 2006; 8:1983-6. [PMID: 16671762 DOI: 10.1021/ol0600638] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction; see text] Aza-enediynes (C,N-dialkynyl imines) undergo thermal aza-Bergman rearrangement to beta-alkynyl acrylonitriles through 2,5-didehydropyridine (2,5-ddp) intermediates. Certain aza-enediynes also undergo an alternative process affording enediynes and fumaronitriles. Studies employing a specifically (l3)C-labeled aza-enediyne show that the conversion to enediyne is second order in aza-enediyne, proceeds by a "head-to-tail" coupling, and affords the (Z)-enediyne.
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Affiliation(s)
- Liping Feng
- Division of Medicinal Chemistry, College of Pharmacy and Institute for Cellular and Molecular Biology, The University of Texas at Austin, 78712, USA
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Nadipuram AK, Kerwin SM. Thermal cyclization of 1,2-dialkynylimidazoles to imidazo[1,2-a]pyridines. Tetrahedron 2006. [DOI: 10.1016/j.tet.2005.11.084] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Intra- and intermolecular trapping of cyclopentapyrazine carbenes derived from 1,2-dialkynylimidazoles. Tetrahedron Lett 2006. [DOI: 10.1016/j.tetlet.2005.11.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Li H, Yang H, Petersen JL, Wang KK. Biradicals/Zwitterions from Thermolysis of Enyne−Isocyanates. Application to the Synthesis of 2(1H)-Pyridones, Benzofuro[3,2-c]pyridin-1(2H)-ones, 2,5-Dihydro-1H-pyrido[4,3-b]indol-1-ones, and Related Compounds. J Org Chem 2004; 69:4500-8. [PMID: 15202908 DOI: 10.1021/jo049716t] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Thermolysis of benzannulated enyne-isocyanates 13 and enyne-isocyanates 36 and 37 promoted the cycloaromatization reactions to generate in situ O,4-didehydro-2-hydroxyquinolines and O,4-didehydro-2-hydroxypyridines, respectively, as reactive intermediates. These cycloaromatized intermediates could be captured either as biradicals and/or as zwitterions depending on the nature of the substituent at the alkynyl terminus. The intermediate derived from cycloaromatization of 13a bearing a phenyl substituent could be regarded as biradical 14, which then abstracts hydrogen atoms from gamma-terpinene leading to 2(1H)-quinolinone 15. Alternatively, the same intermediate could also be regarded as zwitterion 14', which then undergoes an initial hydride abstraction from gamma-terpinene followed by protonation to produce 15. The presence of a 2-phenylethyl substituent in 13b and 37a or a 2-methylphenyl substituent in 37b also allowed the resulting intermediates to be captured intramolecularly either as biradicals or as zwitterions, producing 2(1H)-quinolinone 19, 2(1H)-pyridone 39, and benzopyranopyridine 43, respectively. On the other hand, with a 2-methoxyphenyl, a 2-(dimethylamino)phenyl, or a 3-methoxypropyl substituent, the chemical behavior of the cycloaromatized adduct could be best accounted for in terms of a zwitterionic intermediate leading to benzofuro[3,2-c]quinolin-6(5H)-one (20), 5,11-dihydro-11-methyl-6H-indolo[3,2-c]quinolin-6-one (25), benzofuro[3,2-c]pyridin-1(2H)-one 44, 2,5-dihydro-2,5-dimethyl-1H-pyrido[4,3-b]indol-1-one 46, and related compounds. Interestingly, thermolysis of 37f bearing a 2-(methoxymethyl)phenyl substituent at the alkynyl terminus produced the unexpected benzopyranopyridine 56 as the major product in a process involving the cleavage of the bond between the methoxyl oxygen and the adjacent methylene carbon. The efficiency and selectivity of the cycloaromatization reaction could also be enhanced by the introduction of 1.1 to 10 equiv of dimethylphenylsilyl chloride to the reaction mixture to capture the resulting zwitterion.
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Affiliation(s)
- Hongbin Li
- Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045, USA
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Feng L, Kumar D, Birney DM, Kerwin SM. α,5-Didehydro-3-picoline Diradicals from Skipped Azaenediynes: Computational and Trapping Studies of an Aza-Myers−Saito Cyclization. Org Lett 2004; 6:2059-62. [PMID: 15176818 DOI: 10.1021/ol049266r] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
[reaction: see text] On the basis of density functional calculations, the isomerization of skipped azaenediynes (C-alkynyl-N-propargylimines) to azaenyne allenes and subsequent rapid aza-Myers-Saito cyclization to alpha,5-didehydro-3-picoline were predicted. We prepared the N-propargylimine of 1-phenyl-3-tri(isopropyl)silylprop-2-yn-1-one, which undergoes proto-desilylation and isomerization to an azaenyne allene when treated with tetrabutylammonium fluoride. In the presence of 1,4-cyclohexadiene, this azaenyne allene affords 6-phenyl-3-picoline and other products corresponding to the trapping of an alpha,5-didehydro-3-picoline diradical.
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Affiliation(s)
- Liping Feng
- Division of Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, Austin, Texas 78712, USA
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Winkler M, Cakir B, Sander W. 3,5-PyridyneA Heterocyclic meta-Benzyne Derivative. J Am Chem Soc 2004; 126:6135-49. [PMID: 15137779 DOI: 10.1021/ja039142u] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
3,5-Pyridyne (3) has been generated by flash vacuum pyrolysis of 3,5-diiodopyridine (20) and 3,5-dinitropyridine (21) and characterized by IR spectroscopy in cryogenic argon matrices. The aryne can clearly be distinguished from other side products by its photolability at 254 nm, inducing a rapid ring-opening presumably to (Z)-1-aza-hex-3-ene-1,5-diyne. As byproducts of the pyrolysis, HCN and butadiyne were identified, together with traces of acetylene, cyanoacetylene, (E)-1-aza-hex-3-ene-1,5-diyne, and the 3-iodo-5-pyridyl radical (from 20). Several pathways for rearrangements and fragmentations of 3 and of the parent meta-benzyne (1) have been explored computationally by density functional theory and ab initio quantum chemical methods. The lowest energy decomposition pathway of biradicals 1 and 3 is a ring-opening process accompanied by hydrogen migration, leading to (Z)-hex-3-ene-1,5-diyne [(Z)-10] and (Z)-3-aza-hex-3-ene-1,5-diyne [(Z)-24], respectively. Both reactions require activation energies of 45-50 kcal mol(-1). Mechanisms leading from (Z)-24 or directly from 3 to the experimentally observed byproducts are discussed. Upon replacement of the C(5)H moiety by N in meta-benzyne, high-level calculations predict a modest shortening of the interradical distance by 5-7 pm and a reduction of the singlet-triplet energy splitting by 3 kcal mol(-1), in good agreement with isodesmic equations, according to which the singlet ground state of 3 is destabilized relative to 1 by 3-4 kcal mol(-1). In contrast to 3,5-borabenzyne (2), which is found to be doubly aromatic, nucleus-independent chemical shifts of 3 are almost identical to that of pyridine, indicating the absence of paramagnetic ring current effects that may be associated with "in-plane antiaromaticity". As compared with 1, the overall perturbation caused by the nitrogen atom in 3 is weak, and four electron, three center interaction is of minor importance in this molecule.
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Affiliation(s)
- Michael Winkler
- Lehrstuhl für Organische Chemie II der Ruhr-Universität Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
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Feng L, Kumar D, Kerwin SM. An extremely facile aza-Bergman rearrangement of sterically unencumbered acyclic 3-aza-3-ene-1,5-diynes. J Org Chem 2003; 68:2234-42. [PMID: 12636386 DOI: 10.1021/jo0267192] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The factors that affect the kinetics of the aza-Bergman cyclization of aza-enediynes (C,N-dialkynyl imines) have not previously been elucidated. Here we report our kinetic studies of the aza-Bergman reactions of a series of 6-triisopropylsilyl and 6-unsubstituted 1-phenyl-4-aryl-3-aza-3-ene-1,4-diynes in which the aryl group is phenyl, o-(methoxy)phenyl, or p-(methoxy)phenyl. These aza-enediynes are prepared as single isomers in modest yield from the corresponding 1-aryl-3-(triisopropylsilyl)propynone oximes. These aza-enediynes undergo aza-Bergman reaction followed by a rapid retro-aza-Bergman cyclization to afford beta-alkynyl acrylonitrile products. In no case are products corresponding to trapping the intermediate 2,5-didehydropyridine diradical isolated. While the rate of aza-Bergman cyclization is not greatly affected by the nature of the 4-aryl substituent, the rate is very dependent on the nature of the 6-substituent. 1-Phenyl-4-aryl-3-aza-3-ene-1,5-diynes that lack a 6-substituent undergo aza-Bergman cyclization spontaneously at 20 degrees C with first-order half-lives of 36-78 min. The effect of solvent on the kinetics of aza-Bergman cyclization of 1,4-diphenyl-3-aza-3-ene-1,5-diyne was investigated. The rate of this cyclization is solvent dependent, proceeding more rapidly in less polar solvents.
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Affiliation(s)
- Liping Feng
- Division of Medicinal Chemistry, College of Pharmacy, The University of Texas at Austin, 78712, USA
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