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 Baldwin's rule. Finally Baylis-Hillman reaction products were used as scaffolds for diversity-oriented sultam syntheses.