Five-and seven-membered sultam derivatives were conveniently synthesized via intra-or intermolecular Michael additions and an improved vinyl sulfonamide Baylis–Hillman reaction. Two different cyclization pathways were explored for the oxa-Michael reaction. A good solvent was discovered for an otherwise sluggish ketone-type Baylis–Hillman reaction in which vinyl sulfonamide ketones were used as the precursors. Furthermore, a strong ...