The reaction of O-(p-chlorophenoxy)aniline hydrochloride (I) with ethyl chlorocarbonate (A) in pyridine ether gives ethyl O-(p-chlorophenoxy)phenylcarbanilate (II), which is condensed with N-carbetoxypiperazine (B) by means of Na2O or NaOCH3 in refluxing benzene to afford ethyl 4-[(O-(p-chlorophenoxy)phenyl)carbamoyl]-1-piperazine carboxylate (III). This product is finally decarboxylated and cyclized with P2O5 in refluxing POCl3.
The condensation of 11-amino-2-chlorodibenzo[b,f][1,4]oxazepine (IV) with piperazine (A) by means of aluminum chloride at 100 C.