The reaction of O-propylphenyl azide with di-n-propylamine

Nitration of n-propylbenzene resulted in O-nitro-n-propylbenzene. Reduction of this compound gave o-n-Propylphenyl azide was prepared by diazotization of o-n-propylaniline followed by treatment with sodium azide. Photolysis of o-n-propylphenyl azide in di-n-propyl-amine yielded two new azepines, 2-di-n-propylamino-3n-propyl-3H azepine and 2-di-n-propylamino-7-n-propy1-7H-azepine. Their structures were assigned on the basis of their physical properties (i.e. I.R., U.V., N.M.R., N.S. and elemental analysis). Photolysis of the azide at room temperature gave 26.9% o-n-propylaniline and 4.3% 2-di-n-propylamino-3-n-propy1-3H azepine, but when the photolysis was carried out in the presence of the triplet photosensitizer (xanthen-9-one) the yield of o-n-propylaniline was increased to 34.6% and the yield of 2-di-n-propylamino-3n-propy1-3H-azepine was decreased to 1.4%. Photolysis at the reflux temperature of di-n-propylamine (110c0) resulted in the formation of 42% o-n-propylaniline, 19.9% 2-di-n-propylamino-3n-propy1-3H azepine, 3.7% 2-di-n-propyl-amino 7n-propy1-7H azepine and 4.5% 2-methylindoline. Based on these results, arguments are presented which suggest that singlet n-propylphenyl nitrene, which is in equilibrium with azabicyclic intermediates, is responsible for the formation of these two new asepines, 2-di-n-propylamino 3n-propyl-3H azepines and 2-di-n-propylamino-7n-propyl-7H azepine. Also, a mechanistic scheme is proposed to explain the formation of all products obtained from the photoysis of O-n-propylphenyl azide