Salicylaldehyde (1) was reacted with aniline to afford 2-[(E)-(phenylimino)methyl]phenol (2). The reduction of (2) by NaBH 4 gave 2-((phenylamino)methyl)phenol (3) which was reacted with chloroacetyl chloride to give 2-chloro-N-(2-hydroxybenzyl)-N-phenylacetamide (4). Compound (4) was cyclized to 4-phenyl-4,5-dihydrobenzo[f][1,4]oxazepin-3(2H)-one (5) by NaOH in ethanol solution. The treatment of compound (5) with P 2 S 5 gave corresponding 4-phenyl-4,5-dihydrobenzo[f][1,4]oxazepin-3(2H)-thione (6). The structures of (5) and (6) were determined by 1 H NMR and IR spectra. The optimized structural parameters and vibrational frequencies of (5) and (6) were calculated by DFT with 6-31G(d,p) basis set. The mechanism of the cyclization reaction was studied by RHF with the standard 3-21G basis set.