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Please use this identifier to cite or link to this item: http://repository.iitr.ac.in/handle/123456789/20605
Title: Asymmetric synthesis of 3-benzofuranones through 5-exo-trig cyclization of 4-nitroaryl olefins
Authors: Verma N.
Kumar S.
Ahmed, Naseem
Published in: Tetrahedron Letters
Abstract: Organo-catalyzed aldol condensation of 2-hydroxyacetophenone and 4-nitrobenzaldehyde underwent regio- and enantioselective cyclization via intramolecular 5-exo-trigonal cyclization to give 4-nitroaryl-3-benzofuranones. The product formation indicated that the proline bases (organocatalysts) suppressed the effect of carbonyl group by iminium ion formation and hence Michael addition is not possible. The conjugation effect moved toward 4-nitroaryl moiety suitable for 5-exo-trig cyclization (Baldwin's rule). Thus, the non-equilibrating intermediates (NEIs) which gave in enantio-enriched 3-benzofuranones. A high enantioselectivity (80–96.6%) was obtained with (S)-pyrrolidinyl-tetrazole V under a metal-free condition. © 2016 Elsevier Ltd
Citation: Tetrahedron Letters, 57(31): 3547-3550
URI: https://doi.org/10.1016/j.tetlet.2016.06.118
http://repository.iitr.ac.in/handle/123456789/20605
Issue Date: 2016
Publisher: Elsevier Ltd
Keywords: 3-Benzofuranones
4-Nitroarylolefins
5-exo-trig cyclization
Enantioselective
Organocatalyst
ISSN: 404039
Author Scopus IDs: 56666842900
56167238700
7401846814
Author Affiliations: Verma, N., Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247 667, India
Kumar, S., Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247 667, India
Ahmed, N., Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee, 247 667, India
Funding Details: Authors thank the BRNS , Mumbai India for financial support and HRMS facility from fist DST, New Delhi, Kamal from IIT Ropar for Chiral HPLC and CSIR, New Delhi for awarding SRF to N.V. and S.K. Council of Scientific and Industrial Research, India, CSIR; Board of Research in Nuclear Sciences, BRNS; Department of Science and Technology, Government of West Bengal, DST
Corresponding Author: Ahmed, N.email: nasemfcy@iitr.ac.in
Appears in Collections:Journal Publications [CY]

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