Synthesis and some transformations of new acetophenones with carbamate function

Abstract

Acylation of methyl- N -phenyl-, 2-(morpholin-4-yl)ethylphenyl-, 2-(pyridin-2-yl)ethylphenyl-carbamates with acetic anhydride in polyphosphoric acid at 50-55°C for 3 h proceeds in the para -position to the carbamate grouping to form the corresponding acetophenones. Acylation under similar conditions of methyl 2-(methoxyphenyl)carbamate occurs in the para -position to the methoxy group with the formation of methyl N -(5-acetyl-2-methoxyphenyl)carbamate. The interaction of para - and ortho -acetyl-substituted methyl- N -phenylcarbamate with N -bromosuccinimide, copper(II) acetate in the presence of dimethylformamide at 80°C and with chloro- and hydrobromic acids in the presence of DMSO in ethyl acetate at 30-33°C yielded methyl {4(2)-[(dimethylamino)(oxo)-acetyl]phenyl}- and N -[4(2)-(2-bromo-2-chloroacetyl)phenyl]-carbamates. Condensation of 2-morpholinoethyl [(pyridin-2-yl)ethyl] N -(4-acetylphenyl)carbamates with 4-methoxybenzaldehyde in the presence of a methanolic KOH solution gave the corresponding chalcones.