Reaction of N-substituted bromomethanesulfonamides with 2 equiv of potassium carbonate and an α-halo ketone, ester, or nitrile leads directly to 3-substituted β-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 β-sultam products can be subsequently manipulated to give bicyclic products.Key words: β-sultams, intramolecular SN2 displacement, sulfonamides, ring closing metathesis, four-membered heterocycles.
Stereoselective Synthesis of the I–L Fragment of the Pacific Ciguatoxins
