Synthesis of lactams and other nitrogen heterocycles by intramolecular cyclizations of carbamates and acyl derivatives of aminosulfones

The α sulfonyl carbanions obtained by the treatment of the carbamate derivatives of aminosulfones (type I) with LHMDS in THF at −78°C, underwent cyclization to give five-, six-, and seven-membered cyclic lactams in excellent yields. Cyclization of the N-acyl derivatives of the type II led to the formation of substituted dihydropyrrolidines in good yields. The scope and limitations of this cyclization strategy to access functionalized nitrogen containing ring systems have been examined.