Direct catalytic enantio- and diastereoselective aldol reaction of thioamides |
| |
Authors: | Iwata Mitsutaka Yazaki Ryo Chen I-Hon Sureshkumar Devarajulu Kumagai Naoya Shibasaki Masakatsu |
| |
Affiliation: | Institute of Microbial Chemistry, Tokyo, 3-14-23 Kamiosaki, Tokyo 141-0021, Japan. |
| |
Abstract: | A direct catalytic asymmetric aldol reaction of thioamides using a soft Lewis acid/hard Br?nsted base cooperative catalyst comprising (R,R)-Ph-BPE/[Cu(CH(3)CN)(4)]PF(6)/LiOAr is described. Exclusive enolate generation from thioacetamides through a soft-soft interaction with the soft Lewis acid allowed for a direct aldol reaction to α-nonbranched aliphatic aldehydes, which are usually susceptible to self-condensation under conventional basic conditions. A hard Lewis basic phosphine oxide has emerged as an effective additive to constitute a highly active ternary soft Lewis acid/hard Br?nsted base/hard Lewis base cooperative catalyst, enabling a direct enantio- and diastereoselective aldol reaction of thiopropionamides. Strict control of the amount of the hard Lewis base was essential to drive the catalytic cycle efficiently with a minimized retro-aldol pathway, affording syn-aldol products with high stereoselectivity. Divergent transformation of the thioamide functionality is an obvious merit of the present aldol methodology, allowing for a facile transformation of the aldol product into the corresponding aldehyde, ketone, amide, amine, and ketoester. An aldehyde derived from the direct aldol reaction was subjected to a second direct aldol reaction, which proceeded in a catalyst-controlled manner to provide 1,3-diols with high stereoselectivity. |
| |
Keywords: | |
本文献已被 PubMed 等数据库收录! |
|