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Enantioselective conjugate addition of ketones to nitroalkenes catalyzed by pyrrolidine‐sulfamides
Author(s) -
Wang Jinjia,
Lao Jinhua,
Du Quansheng,
Nie Shaozhen,
Hu Zhipeng,
Yan Ming
Publication year - 2012
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.21987
Subject(s) - pyrrolidine , chemistry , enantioselective synthesis , sulfamide , catalysis , organocatalysis , conjugate , cyclohexanone , stereocenter , isopropyl , nitroalkene , organic chemistry , aryl , combinatorial chemistry , mathematical analysis , alkyl , mathematics
A series of chiral pyrrolidine‐sulfamides were prepared and examined as the catalysts for conjugate addition of ketones to nitroalkenes. Benzoic acid was identified as the most efficient additives for the transformation. Excellent enantioselectivities, diastereoselectivities, and yields were achieved for the reaction of cyclohexanone with β‐aryl nitroethylenes under solvent free conditions. β‐Isopropyl nitroethylene is also applicable and the product could be obtained with excellent enantioselectivity after extended reaction time. A comparison of the catalytic behaviors of pyrrolidine‐sulfamide organocatalysts with different side chains demonstrates that the enantioselectivity is mainly controlled by the chiral pyrrolidine unit and the additional chiral center at the side chain exerts neglectable effects. The H‐bonding interaction between the sulfamide and the nitro group is proposed to be crucial for the activation of the nitroalkene and the constitution of well‐organized transition state. Chirality, 2012. © 2012 Wiley Periodicals, Inc.