Highly enantioselective organocatalytic Biginelli reaction.
A series of binol- and H8-binol-based phosphoric acids have for the first time been evaluated for their ability to catalyze Biginelli reactions of aldehydes, thiourea or urea, and beta-keto esters. A new chiral phosphoric acid, derived from 3,3'-diphenyl-H8-binol, exhibited superior catalytic activity and enantioselectivity compared to its structural analogues, affording high enantioselectivities ranging from 85 to 97% ee with a wide scope of substrates. A metal-free preparation of optically active monastrol was achieved on the basis of the current process.
Chen
Xiao-Hua
XH
Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemistry, University of Science and Technology of China, Hefei 230026, China.
Xu
Xiao-Ying
XY
Liu
Hua
H
Cun
Lin-Feng
LF
Gong
Liu-Zhu
LZ