Journal of Molecular Catalysis A-Chemical, Vol.288, No.1-2, 28-32, 2008
Synthesis of 2-substituted 3,4-dihydro-2H-1,4-benzoxazines through ligandless copper-catalyzed cyclization of hydroxysulfonamides under phase-transfer catalysis conditions
The ring closing under solid-liquid phase-transfer catalysis conditions (SL-PTC) of hydroxysulfonamides 7, bearing a leaving group in the ortho position of the aryl moiety, generates 2-substituted-3,4-dihydro2H-1,4-benzoxazines 4 in good to excellent yields. In the case of hydroxysulfonamides 7 bearing a bromine or iodine atom as a leaving group, a copper(l) salt is used to enable the reaction to occur. (C) 2008 Elsevier B.V. All rights reserved.