Question

Draw a stepwise mechanism for the following reaction of a Grignard reagent with a cyclic amide.

Short answer

Grignard reaction occurs when the alkyl part of the Grignard reagent attacks at the carbonyl carbon. Subsequently, the hydrolysis forms the substituted alcohol.

The excess Grignard reagent substitutes another alkyl group via the bimolecular substitution reaction.

Step-by-step solution

Grignard reaction

Grignard reaction occurs when the alkyl part of the Grignard reagent attacks at the carbonyl carbon. Subsequently, the hydrolysis forms the substituted alcohol.

The excess Grignard reagent substitutes another alkyl group via the bimolecular substitution reaction.

Explanation

In the first step, the anion part of the ethyl magnesium bromide attacks at the carbonyl carbon followed by the hydrolysis.

In the second step, the other ethyl magnesium bromide molecule attacks at the alcoholic carbon and eliminates the hydroxide ion.

The mechanism is shown as:

Grignard reaction mechanism