Synthesis of some new N,N′-diarylsubstituted methylene-bis-dihydro-2H-1,3-benzoxazines

The synthesis of a new series of six-membered N,N′-diarylsubstituted methylene-bis-dihydro-2H-1,3-benzoxazines (5a–e) was achieved in excellent yields by Mannich-type condensation of N,N′-diarylsubstituted methylene-bis-o-hydroxybenzyl amines (4a–e) with formaldehyde in chloroform at reflux. These amines (4a–e) were obtained by the reduction of N,N′-diarylsubstituted methylene-bis-o-hydroxybenzyl imines (3a–e) with NaBH₄, which inturn were obtained by the condensation of methylene-bis-salicylaldehyde (2) with various substituted arylamines.