Organocatalytic Enantioselective Synthesis of Both Diastereomers of α-Hydroxyphosphinates

Racemic α-acylphosphinates and formylphosphinate hydrate were used directly as the substrates in a proline derivative-catalyzed cross aldol reaction with ketones. Because of the preexisting phosphorus stereogenic center, a mixture of two diastereomers of the corresponding α-hydroxyphosphinates was obtained in this reaction. Good to high enantioselectivities (up to 99% ee) were obtained simultaneously for the two diastereomers in good yields. Good diastereoselectivities were also obtained when the reaction generates an additional carbon stereogenic center.

外消旋α-酰基次膦酸酯（racemic α-acylphosphinates）与甲酰基次膦酸酯水合物（formylphosphinate hydrate）直接用作底物，在脯氨酸衍生物（proline derivative）催化下与酮类发生交叉羟醛缩合反应。由于底物预先存在磷手性中心，该反应生成了对应产物α-羟基次膦酸酯（α-hydroxyphosphinates）的两种非对映异构体混合物。两种非对映异构体均同时实现了优异至优秀的对映选择性（最高可达99% 对映体过量值，ee），且反应收率良好。当该反应同时生成额外的碳手性中心时，亦可获得良好的非对映选择性。