Diastereoselective Henry Reaction Catalyzed by Guanidine-Thiourea Bifunctional Organocatalyst
作者:Kazuo Nagasawa、Yoshihiro Sohtome、Nobuko Takemura、Toshitsugu Iguchi、Yuichi Hashimoto
DOI:10.1055/s-2005-922770
日期:——
A highly diastereoselective Henry reaction (diastereomer ratio of 84:16 to 99:1) of α-substituted aldehydes with nitromethane was developed using guanidine-thiourea bifunctional catalyst 1. N,N-Dibenzyl-protected α-amino aldehydes (2a, 2d-h) and α-hydroxy aldehydes protected as silyl ethers (2i-j) were suitable substrates. The matched combination of this catalytic system, i.e., S-aldehydes and (R,R)-1
使用胍-硫脲双功能催化剂开发了 α-取代醛与硝基甲烷的高度非对映选择性亨利反应(非对映异构体比例为 84:16 至 99:1) 1. N,N-二苄基保护的 α-氨基醛 (2a, 2d- h) 和保护为甲硅烷基醚 (2i-j) 的 α-羟基醛是合适的底物。这种催化体系的匹配组合,即 S-醛和 (R,R)-1 催化剂,可以从由 1 催化的亨利反应的不对称形式的过渡态来理解。