Question

Predict the major product of each of the following reactions:

Short answer

Answer

Step-by-step solution

Step-by-Step SolutionStep 1: Reaction of epoxides (Ring-opening)

The epoxide ring is opened by a reaction with acid (HX) in ether, and the substitution pattern of the carbons in the epoxide ring tells where the ring-opening reaction occurs. The more hindered carbon (tertiary) is attacked from the backside, and cleavage occurs.

The major product of the reaction in (a)

1. The ring-opening reaction in acid-catalyzed occurs at that carbon which is more hindered if one of the epoxide carbons is tertiary. In this reaction, the marked carbon is tertiary because two methyl groups are attached. The major product formed is,

Ring-opening reaction

The major product of the reaction in (b)

b. In this reaction, the tertiary carbon of the epoxide ring is marked by the arrow. The ring-opening reaction takes place, and the major product formed is shown below,

Ring-opening reaction