Lithiation of 1-chloromethylbenzotriazole: generation and elaboration of benzotriazolyloxiranes.

1-Benzotriazolylchloromethyllithium generated from 1-chloromethylbenzotriazole (1) and LDA reacts with enolizable and nonenolizable ketones to give benzotriazolyloxiranes 2a-g in good yields. The oxiranyllithiums 4a-d generated from 2a-d and n-BuLi at -78 degrees C were trapped by a variety of electrophiles to give oxiranyl derivatives 5a-j in good to excellent yields. Lewis-acid-promoted nucleophilic ring opening of benzotriazolyloxiranes 2a,f,g with allyltrimethylsilane gave the corresponding 1,7-octadien-4-ols 6a-c in 68-75% yield. Hydrolysis of alpha-acylbenzotriazolyloxiranes 5g,h provided 3-hydroxy-1,2-diones 7a and 7b in 73 and 86% yield, respectively.