Synthesis, infrared spectral studies and theoretical calculations of 4-phenyl-4,5-dihydrobenzo[f][1,4]oxazepin-3(2H)-one (thione)

Salicylaldehyde (1) was reacted with aniline to afford 2-[(E)-(phenylimino)methyl]phenol (2). The reduction of (2) by NaBH4 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 P2S5 gave corresponding 4-phenyl-4,5-dihydrobenzo[f][1,4]oxazepin-3(2H)-thione (6). The structures of (5) and (6) were determined by 1H 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.