A series of novel tricyclic O,N-heterocycles, [1,2,4]triazolo[3,2-d][1,5]benzoxazepin-2-thiones 7 were achieved via acid-induced ring closure of the geminal arylazo isothiocyanate compounds 5 which were derived from substituted chroman-4-ones, followed by feasible ring expansion with simultaneous insertion of the nitrogen atom into the carbon skeleton. The X-ray crystal structure of 7d was also described.
H-1,2,3-Diazaphospholes 3a3h were prepared from various ketone acylhydrazones and phosphorus trichlo-ride in the presence of triethylamine. Compounds 3 underwent feasible hetero-Diels-Alder reactions with cyclopen-tadiene to afford the respective anellated [1,2,3]diazaphospholes 4a4d as well as 4a'4d' in moderate yields. The endo rule in the reaction was observed under kinetic control conditions.
