Tin-mediated enantioselective aldol-type reaction for the asymmetric synthesis of α-substituted serines utilizing an external chiral ligand, (−)-sparteine
作者:Shigeki Sano、Takahiro Ishii、Toshio Miwa、Yoshimitsu Nagao
DOI:10.1016/s0040-4039(99)00406-2
日期:1999.4
The enantioselective aldol-type reaction of ethyl 3,6-diethoxy-2,5-dihydro-2-pyrazinecarboxylate (1) with achiral aldehydes 2a-d was investigated by employing Sn(OSO2CF3)2-triethylamine in the presence of (−)-sparteine. Not only a stoichiometric amount, but also 0.3 mol equiv. of (−)-sparteine promoted the highly enantioselective aldol-type reaction.
3,6-二乙氧基-2,5-二氢-2-吡嗪羧酸乙酯(1)与非手性醛2a-d的对映选择性醛醇型反应是通过在反应存在下使用Sn(OSO 2 CF 3)2-三乙胺进行的。 (-)-黄连。不仅是化学计量的量,而且是0.3摩尔当量。(-)-天冬氨酸的合成促进了高度对映选择性的醛醇型反应。