Generic synthesis of β-sultams via domino alkylation of bromomethanesulfonamides

Reaction of N-substituted bromomethanesulfonamides with 2 equiv of potassium carbonate and an alpha-halo ketone, ester, or nitrile leads directly to 3-substituted beta-sultams. The first step is intermolecular and is followed by an intramolecular alkylation. The process is particularly efficient when diethyl bromomalonate and 3-chloro-2-butanone are involved. In the latter example, no competitive cyclization to form a six-membered ring is seen. The functional groups in certain of the beta-sultam products can be subsequently manipulated to give bicyclic products.