Syntheses of five- and seven-membered ring sultam derivatives by Michael addition and Baylis–Hillman reactions

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 base caused vinyl sulfonamide ketones to undergo 5-endo-trig intramolecular cyclizations, which are disfavored according to Baldwinʹs rule. Finally Baylis–Hillman reaction products were used as scaffolds for diversity-oriented sultam syntheses.