Catalysis of Mukaiyama Aldol Reactions by a Tricyclic Aluminum Alkoxide Lewis Acid
作者:Steven M. Raders、John G. Verkade
DOI:10.1021/jo9009134
日期:2009.8.7
The Mukayiama aldolreaction of aldehydes is efficiently accomplished with a low concentration of the dimeric alumatrane catalyst 2 at mild or subambient temperatures. Our protocol tolerates a wide variety of electron-rich, neutral, and deficient aryl, alkyl, and heterocyclic aldehydes. A wide variety of enol silyl ethers are also tolerated. An intermediate that was isolated provides mechanistic information
We have developed an efficient vinylogous Mukaiyamaaldolreaction of 2-(trimethylsilyloxy)furan with various aromatic aldehydes mediated by bismuth triflate in lowcatalystloading (1 mol %). The reaction proceeds rapidly and affords the corresponding 5-(hydroxy(aryl)methyl)furan-2(5H)-ones in high yields with good to very good diastereoselectivities (dr up to >98:2). Such selectivities, albeit previously
N-Heterocyclic Carbene Catalyzed Vinylogous Aldol Reaction of 2-(Trimethylsilyloxy)furan and Aldehydes
作者:Lin He、Guang-Fen Du、Cheng-Zhi Gu、Bin Dai
DOI:10.1055/s-0030-1258551
日期:2010.10
A N-Heterocyclic carbenes (NHC) catalyzed vinylogous aldol reaction between 2-(trimethylsilyloxy)furan and aldehydes has been developed, providing γ-substituted butenolides in high yields with good diastereoselectivities. Furthermore, the catalyst loading can be reduced to 1 mol%.
The asymmetricdirect vinylogous aldolreaction of unactivated γ-butenolide with aldehydes has been developed, giving the corresponding 5-(1′-hydroxy)butenolide derivatives in high yields (up to 93%) and enantioselectivities (up to 83% ee) under mild conditions.
Organocatalytic asymmetric direct vinylogous aldol reactions of γ-crotonolactone with aromatic aldehydes
作者:Sunil V. Pansare、Eldho K. Paul
DOI:10.1039/c0cc04191b
日期:——
The direct aldol reaction of γ-crotonolactone and various aromatic aldehydes is catalyzed by bifunctional aminothiourea and aminosquaramide organocatalysts to provide diastereomerically and enantiomerically enriched 5-substituted 2(5H) furanones (γ-butenolides). The reaction is a simple alternative to the classical vinylogous aldol reaction of silyloxy furans.