The addition of sterically demanding enolsilanes to α-chloro aldehydes results unexpectedly in preferential formation of the anti-PFA product (1,2-syn), while the addition of the corresponding boron enolate furnishes the expected polar FelkinâAnh product (1,2-anti). A stereoinduction model explaining these observations is proposed.
向α-
氯醛中添加空间位阻较大的
乙烯基硅烷,意外地导致优先形成反-PFA产物(1,2-syn),而添加相应的
硼烯醇盐则得到预期的极性Felkin-Anh产物(1,2-anti)。提出了一个解释这些观察结果的立体诱导模型。