INTRAMOLECULAR ANIONIC FRIEDEL-CRAFTS EQUIVALENTS - AN EXPEDITIOUS SYNTHESIS OF 4H-1,2-BENZOTHIAZIN-4-ONE 1,1-DIOXIDES FROM N-ARYLSULFONYLATED AMINO-ACIDS

Treatment of compounds 1, readily available from amino acids, with exc ess LDA furnishes benzothiazinones 2 in modest to good yields (Table); variations of carbanion-mediated reactions lead to benzothiazepinones (Table, entries 12 and 13) and dibenzothiazepinone (5).