Synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazines through ligandless copper-catalyzed cyclization of hydroxysulfonamide under phase-transfer catalysis conditions

The ring closing under SL-PTC conditions of hydroxysulfonamides 7, bearing a leaving group in the ortho position of the aryl moiety, generates 2-substituted-3,4-dihydro-2H-1,4-benzoxazines 4 in good to excellent yields. In the case of hydroxysulfonamides 7 bearing a bromine or iodine atom as leaving groups, a copper (I) salt is used to enable the reaction to occur