Synthesis of 2-amino-8-benzylidene-4-phenyl-3,4,5,6,7,8-hexahydro- and -5,6,7,8-tetrahydroquinazoline derivatives

Abstract

Base-catalyzed reaction of 2,6-dibenzylidenecyclohexanone and alkylguanidines gave 2-alkylamino-8-benzylidene-4-phenyl-3,4,5,6,7,8-hexahydroquinazolines IVa-c, which were oxidized to 2-alkylamino-8-benzylidene-4-phenyl-5,6,7,8-tetrahydroquinazolines Va-c. The acylamino (VIa-c, VIIa-d, IXa,b) and diacylamino derivatives (VIIIa,b) of the 2-amino-8-benzylidene-4-pheny]-3,4,5,6,7,8-hexahydroquinazoline (II), 2-amino-8-benzylidene-4-phenyl-5,6,7,8-tetrahydroquinazoline (III) and compounds Va-c have also been prepared. These compounds having the E-configuration were converted into the Z isomers XIIa-e by photoisomerization. The structures were confirmed by spectroscopic methods (IR, 1H NMR, 13C NMR).