Efficient synthesis of optically active 4-nitro-cyclohexanones via bifunctional thiourea-base catalyzed double-Michael addition of nitromethane to dienones
作者:Bin Wu、Guo-Gui Liu、Mei-Qiu Li、Yong Zhang、Shao-Yun Zhang、Jun-Ru Qiu、Xiao-Ping Xu、Shun-Jun Ji、Xing-Wang Wang
DOI:10.1039/c0cc05418f
日期:——
Thiourea-modified cinchona alkaloids as bifunctional catalysts and a base could catalyze a stepwise [5+1] cyclization of divinyl ketones with nitromethane via double Michael additions, furnishing optically active 4-nitro-cyclohexanones with good yields, excellent diastereoselectivities (>20 : 1) and high enantiomeric ratios (up to 97 : 3).
addition sequence by chiral primary amine catalysis, which offers a powerful alternative in the design of synthetically useful organocascade reactions (see scheme, EWG=electron‐withdrawing group). This method complements the Diels–Alder reaction for the one‐step synthesis of complex cyclohexane scaffolds with excellent optical purity.
An Acid/Base-Regulated Recyclable Strategy for Homogeneous Cinchona Alkaloid-Derived Primary Amine Organocatalysts in Aldol, Vinylogous Michael and Double-Michael Cascade Reactions
作者:Jingwei Wan、Zhiwei Zhao、Falu Wang、Xuebing Ma
DOI:10.1002/ejoc.201500566
日期:2015.9
reusability of the organocatalysts epi-CDNH2, DeMe-QNNH2 and H-CDNH2 over three cycles was investigated in detail. It was found that the organocatalysts were highly effective with respect to catalytic performance, including the yields and stereoselectivities. Furthermore, the recovered organocatalysts in the tenth cycle retained similar excellent enantioselectivities to fresh organocatalysts. However, the
Double Michael addition of nitromethane to divinyl ketones: A remarkably positive effect of additive
作者:Yongqi Yao、Yingying Liu、Ling Ye、Feng Chen、Xinying Li、Zhigang Zhao、Xuefeng Li
DOI:10.1016/j.tet.2017.03.018
日期:2017.4
An efficient double Michaeladdition of nitromethane to divinyl ketones was established in good to high yields (75–99%). A wide range of cyclohexanones were obtained with excellent diastereocontrol (up to >20:1 dr) and enantioinduction (91–99% ee) in a one-pot fashion. The involvement of basic additive significantly enhanced the reactivity of this cascade sequence.