Synthesis of 1,4-Dihydro-2H-3,1-benzoxazin-2-ones by Hydriodic Acid Mediated Cyclization of tert-Butyl 2-Vinylphenylcarbamates
摘要:
A two-step facile synthesis of 4,4-disubstituted 1,4-dihydro-2H-3,1-benzoxazin-2-ones starting from alpha-substituted 2-aminostyrenes is described. The method involves the hydriodic acid mediated cyclization of t-butyl 2-vinylphenylcarbamate derivatives, which Could be easily prepared by N-t-butoxycarbonylation of alpha-substituted 2-aminostyrene derivatives, under mild conditions.
It has been found that t-butyl 2-vinylphenylcarbamate derivatives underwent iodocyclization on treatment with iodine in the presence of sodium hydrogencarbonate to afford 4-iodomethyl-1,4-dihydro-2H-3,1-benzoxazin-2-one derivatives in generally good yields. The reduction of these 4-iodomethyl derivatives with tributyltin hydride gave the corresponding 4-methyl derivatives in good yields.
Synthesis of 1,4-Dihydro-2H-3,1-benzoxazin-2-ones by Hydriodic Acid Mediated Cyclization of tert-Butyl 2-Vinylphenylcarbamates
A two-step facile synthesis of 4,4-disubstituted 1,4-dihydro-2H-3,1-benzoxazin-2-ones starting from alpha-substituted 2-aminostyrenes is described. The method involves the hydriodic acid mediated cyclization of t-butyl 2-vinylphenylcarbamate derivatives, which Could be easily prepared by N-t-butoxycarbonylation of alpha-substituted 2-aminostyrene derivatives, under mild conditions.