91Ó°ÊÓ

Base-catalyzed epoxide opening occurred when nucleophile attacks at the least hindered epoxide carbon.Many different nucleophiles that can be used for epoxide opening are Grignard reagents, amines, etc.

a. In a base-catalyzed reaction, the epoxide opening occurs when the attack of basic nucleophile takes place at that least hindered carbon. The ¹⁸OH bonded to the least hindered carbon and further reaction with H₂O forms the major product.

Base-catalyzed Epoxide opening reaction

Epoxide opening reaction under acidic conditions

c. In this reaction, the Grignard reagent is added to that epoxide carbon which is least substituted. The first step is the addition of Grignard reagent, and the second step is a reaction under acidic conditions.

Epoxide opening reaction using Grignard reagent