Acyl phosphonates with alpha-halo ketones in the presence of bases at room temperature afford cis- and trans-epoxyphosphonates in good chemical yields and high selectivities using different bases. The diastereoselectivity of this reaction is easily controlled by changing the base. Changing the base from Cs2CO3 to DBU changed the diastereomeric ratio (trans/cis) from 3/2 to 9/1. Moreover, the treatment
在室温下,在碱存在下,具有α-卤代酮的酰基
膦酸酯可提供顺式和反式环氧
膦酸酯,
化学收率好,并且使用不同的碱具有较高的选择性。通过改变碱可以容易地控制该反应的非对映选择性。将碱基从Cs2CO3更改为
DBU,将非对映异构体比例(反式/顺式)从3/2更改为9/1。此外,用
DBU处理反式异构体显示完全转化为相应的顺式异构体。