Catalyst- and solvent-free conditions as an environmentally benign approach to 4-aryl-3-cyano-hexahydro-4H-1,2-benzoxazine-2-oxides

Abstract

Under solvent-free conditions, (E)-2-aryl-1-cyano-1-nitroethenes 1a–l rapidly react with 1-(trimethylsilyloxy)-cyclohex-1-ene (2a) with a complete regio- and diasteroselectivity and leading to the exclusive formation of the cis-fused hexahydro-4H-benzoxazine-2-oxides 3a–l, which were isolated without the need for a work-up procedure in excellent yields.