The N,NЈ-annulated dichlorodiazaphosphole 1 was prepared in 55 % yield by the reaction of cyclohexanone azine (c-HA) with two equivalents of PCl 3 in pyridine. Compound 1 revealed one-dimensional chains in crystal with short intermolecular interactions [3.194(1) Å] between phosphorus atoms of adjacent molecules. Treatment of c-HA with MeLi (2 equiv. in Et 2 O) followed by addition of PCl 3 gave 1 in 33 % yield. An amount of c-HA isomerizes in these * Dr. A. N. Kornev Fax: +7-831-4627497 E-Mail: akornev@iomc.ras.ru [a] G. A. Razuvaev 1173conditions to form corresponding hexahydroindazole derivative 3, which further reacts with 1 to give diazaphosphole 5 as transannulation product. Copper monochloride forms an (1:1) adduct with 5, which was characterized by its X-ray crystal structure. Only one equivalent of PCl 3 reacts with c-HA in Et 2 O/Et 3 N mixture to form diazaphospholium chloride 2 and hexahydroindazole 3.