Die 1,3‐dipolare Cycloaddition von Acetylendicarbonsäure‐estern an 2‐Methyl‐4‐phenyl‐chinazolin‐3‐oxid

Abstract

Abstract The 1,3‐dipolar addition of acetylenedicarboxylic esters (IX and X) to 2‐methyl‐4‐phenyl‐quinazoline 3‐oxide (VIII) in benzene/methanol and benzene/ethanol, respectively, gives the esters XI and XII of 3‐amino‐3‐phenyl‐2‐(2‐acetamidophenyl)‐acrylic acid as main products and the esters XIII and XIV of 2‐methyl‐4‐phenyl‐5 H ‐benzo[d][1,3]diazepin‐5‐carboxylic acid as by‐products. The constitutions of XI and XII are elucidated by acid hydrolysis to the 2‐phenylindole‐3‐carboxylic esters VI and VII, respectively, and by ozonolysis of XII to give benzamide and ethyl o ‐acetamido‐mandelate (IV). The alkaline hydrolysis of XI or XII gives the enamine derivative XVIII, which is hydrolysed by acid to oxindole and benzoic acid. The structure elucidation of XIII and XIV is based on spectroscopic data together with thc formation of XV by alkaline hydrolysis. Mechanisms arc proposed for the reaction paths.