Reactions of 5-aminopyrazoles:: Synthesis of pyrazolo [5′, 1′: 2,3]pyrimido[5,4-b][1,4]-benzothiazines.: A new tetracyclic ring system under microwave irradiation conditions.
A series of pyrazolo[5',1':2,3]pyrimido[5,4-b][1,4]-benzothiazines (4a-0, a new tetracyclic ring system have been prepared under microwave irradiation conditions.