PROCESS FOR PREPARING .DELTA.9,11 AND 21-CHLORO CORTICOSTEROIDS

摘要

Described is a process for the regioselective dehydration of 11-hydroxy steroids using PCl5, PCl3, POCl3 or either SO2Cl2 and imidazole, or PPh3 and CCl4. The disclosed process selectively forms .DELTA.9,11 steroids from eith er 11-.alpha.- or 11-.beta.-hydroxy steroids, and can also be used for the one- step conversion of 11,21-dihydroxy steroids to 21-chloro-.DELTA.9,11 steroid s. Also disclosed are processes for the regioselective conversion of 11-.beta.- chloro steroids to .DELTA.9,11 steroids, and for regioselectively converting an 11,17,21-trihydroxy steroid to a 21-chloro-11,17-dihydroxy steroid.