Transformation of 5,5-diaryl-4,5-dihydro-1,2,4-oxadiazoles to 4-arylquinazolines
摘要:
The transformation of 5,5-diaryl-4,5-dihydro-1,2,4-oxadiazoles to 4-arylquinazolines in boiling acetic anhydride via acyclic 1-acetyloxy-4-aryl-1,3-diaza-1,3-butadienes is described. (C) 2003 Elsevier Science Ltd. All rights reserved.
yields a mixture of at least 8 products, the structures of which are based on spectral and chemical evidence. Both addition of the 1,3-dipole to the carbonylgroup and cycloadditions to the CC double bonds system have been observed. Peri-, regio- and stereo-selectivity of the 1,3-dipole cycloaddition are discussed and rationalized on the basis of simple perturbationtheory approach.
Reaction of benzophenone imine with benzeneoximoyl chloride performed in the presence of triethylamine in diethyl ether affords the title compound, C20H16N2O In the crystalline state, the product exists in two conformations differing in the orientation of the 3-phenyl substituent with respect to the heterocyclic ring. N-H ... N hydrogen bonds link the molecules into chains parallel to the b axis.