A novel organocatalyst for direct asymmetric Michael additions of cyclohexanone to nitroolefins
摘要:
A novel catalyst combining pyrrolidinyl and cyclohexanediamine was designed and synthesized. Only 5 mol% of catalyst loading was required for enantioselective Michael additions of cyclohexanone and nitroolefins affording desired gamma-nitroketones with >99% yield, up to 91% ee and up to >99/1 dr under mild conditions. The enantioselectivity of the product could be further improved to >99% ee after a single recrystallization in petroleum ether/ethyl acetate. (C) 2012 Elsevier B.V. All rights reserved.
[reaction: see text] Readily tunable and bifunctional L-prolinamides as novel organocatalysts have been developed, and their catalytic activities were evaluated in the direct asymmetric Aldolreactions of various aromatic aldehydes and cyclohexanone. High isolated yields (up to 94%), enantioselectivities (up to 99% ee), and anti-diastereoselectivities (up to 99:1) were obtained under the optimal conditions
A novel organocatalyst for direct asymmetric Michael additions of cyclohexanone to nitroolefins
作者:Jun Zhong、Zhi Guan、Yan-Hong He
DOI:10.1016/j.catcom.2012.11.020
日期:2013.2
A novel catalyst combining pyrrolidinyl and cyclohexanediamine was designed and synthesized. Only 5 mol% of catalyst loading was required for enantioselective Michael additions of cyclohexanone and nitroolefins affording desired gamma-nitroketones with >99% yield, up to 91% ee and up to >99/1 dr under mild conditions. The enantioselectivity of the product could be further improved to >99% ee after a single recrystallization in petroleum ether/ethyl acetate. (C) 2012 Elsevier B.V. All rights reserved.