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

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‐5H‐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.

Synthesis of (Z)-3-[amino(phenyl)methylidene]-1,3-dihydro-2H-indol-2-ones using an Eschenmoser coupling reaction

“…Except these synthetically valuable methods, several notes concerning the formation of 3-(aminomethylidene)-1,3-dihydro-2 H -indol-2-ones under different conditions can be found in the literature [ 29 – 31 ].…”

1,3-Dipolar character of 2-vinyl quinazoline 3-oxides; first and second generation cycloaddition products

“…This is in keeping with Stauss' estimation that the 5H-isomer represents at least 90% of the tautomeric mixture of the 2,4,5-trisubstituted benzodiazepine 4. 2 Variable temperature 1 H NMR spectra indicate an enhanced preference for the 5Htautomer as the probe temperature is decreased from 0 The relationship between 5H-10a and the possible minor tautomers, 1H-and 3H-10a is shown in Fig. 4.…”