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Gogoi A, Mukhopadhyay S, Chouhan R, Das SK. Synthesis of benzimidazole-fused 1,4-benzoxazepines and benzosultams spiro-connected to a 2-oxindole core via a tandem epoxide-opening/S NAr approach. Org Biomol Chem 2024; 22:353-363. [PMID: 38086695 DOI: 10.1039/d3ob01613g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
While hundreds of literature reports describe the preparation of spirooxindole-based five- and six-membered heterocycles, the construction of seven-membered heterocyclic rings spiro-connected to a 2-oxindole core has so far been less developed. Herein, we disclose a base-mediated (4 + 3) annulation of spiro-epoxyoxindoles and 2-(2-fluoroaryl)-1H-benzoimidazoles or 2-fluoro-N-arylbenzenesulfonamides toward the synthesis of two new classes of spirooxindole-based polycyclic systems. Mechanistically, this conceptually simple and high atom-economical reaction proceeds via an SN2-like intermolecular epoxide ring-opening, accompanied by a concomitant intramolecular SNAr reaction. From a synthetic aspect, the notable features of the process are its full regioselectivity, operational simplicity using readily available substrates under transition-metal-free conditions, high yields, and broad substrate scope.
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Affiliation(s)
- Abhijit Gogoi
- Department of Chemical Sciences, Tezpur University, Napaam, Tezpur, Assam, 784028, India.
| | - Subhamoy Mukhopadhyay
- Department of Chemical Sciences, Tezpur University, Napaam, Tezpur, Assam, 784028, India.
| | - Raju Chouhan
- Department of Chemical Sciences, Tezpur University, Napaam, Tezpur, Assam, 784028, India.
| | - Sajal Kumar Das
- Department of Chemical Sciences, Tezpur University, Napaam, Tezpur, Assam, 784028, India.
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Rajput D, Kumar A, Jandial T, Karuppasamy M, Bhuvanesh N, Kumar RS, Almansour AI, Sridharan V. Microwave-Assisted Copper(II)-Catalyzed Cascade Cyclization of 2-Propargylamino/Oxy-Arylaldehydes and O-Phenylenediamines: Access to Densely Functionalized Benzo[ f]Imidazo[1,2- d][1,4]Oxazepines and Benzo[ f]Imidazo[1,2- d][1,4]Diazepines. J Org Chem 2022; 87:8956-8969. [PMID: 35765119 DOI: 10.1021/acs.joc.2c00671] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A highly efficient microwave-assisted copper(II)-catalyzed cyclization cascade was established starting from readily accessible O/N-propargylated 2-hydroxy or 2-aminobenzaldehydes and o-phenylenediamines to synthesize densely functionalized imidazo[1,2-d][1,4]oxazepines and imidazo[1,2-d][1,4]diazepines in high yields (up to 93%). This one-pot two-step process was found to be highly atom economical (-H2O, -H2) and operationally simple and enabled the generation of two new heterocycle rings (seven- and five-membered) and three new C-N bonds in a single synthetic operation. These reactions well tolerated a variety of substituents including electron-donating and electron-withdrawing groups and furnished the desired fused heterocycles in high yields under microwave irradiation in a very short reaction time. The mechanism of the established protocol involves sequential imine formation-intramolecular cyclization-air oxidation followed by 7-exo-dig cyclization steps. A comparative study between the microwave-assisted approach and conventional heating was also performed to demonstrate the advantages of the microwave-assisted protocol in terms of high yield and shorter reaction time.
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Affiliation(s)
- Diksha Rajput
- Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), District-Samba, Jammu 181143, J&K, India
| | - Atul Kumar
- Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), District-Samba, Jammu 181143, J&K, India
| | - Tanvi Jandial
- Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), District-Samba, Jammu 181143, J&K, India
| | - Muthu Karuppasamy
- Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), District-Samba, Jammu 181143, J&K, India
| | - Nattamai Bhuvanesh
- Department of Chemistry, Texas A & M University, College Station, Texas 77843, United States
| | - Raju Suresh Kumar
- Department of Chemistry, College of Sciences, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - Abdulrahman I Almansour
- Department of Chemistry, College of Sciences, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia
| | - Vellaisamy Sridharan
- Department of Chemistry and Chemical Sciences, Central University of Jammu, Rahya-Suchani (Bagla), District-Samba, Jammu 181143, J&K, India
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Das J, Borah BJ, Das SK. Construction of Benzosultam‐Containing Fused‐ and Linked‐Biheterocycles by a Cascade Double Nucleophilic Cyclization. European J Org Chem 2022. [DOI: 10.1002/ejoc.202101421] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Jonali Das
- Tezpur University Chemical Sciences Tezpur 784028 Tezpur INDIA
| | | | - Sajal Kumar Das
- Tezpur University Chemical Sciences Napaam 784028 Tezpur INDIA
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Banerjee A, Panda G. Transition metal-free, base mediated one-pot approach for the construction of the benzo[ b][1,4,5]oxathiazepine 1-oxide core. Org Biomol Chem 2022; 20:7112-7126. [DOI: 10.1039/d2ob01158a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Protocol for synthesising selected separable diastereomers of benzo[b][1,4,5]oxathiazepine 1-oxides via intermolecular epoxide ring opening by o-halogenated NH-sulfoximine followed by cyclisation and configurations were assigned by 2D NMR and X-ray crystallography.
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Affiliation(s)
- Arpita Banerjee
- Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, BS-10/1, Sector 10, Jankipuram Extension, Sitapur Road, P.O. Box 173, Lucknow 226031, India
| | - Gautam Panda
- Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, BS-10/1, Sector 10, Jankipuram Extension, Sitapur Road, P.O. Box 173, Lucknow 226031, India
- Academy of Scientific and Innovative Research, New Delhi 110001, India
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