| abstract |
Described is a process for the regioselective dehydration of 11-hydroxynsteroids using PCl 5 , PCl 3 , POCl 3 or either SO 2 Cl 2 and imidazole,nor PPh 3 and CCl 4 . The disclosed process selectively formsnΔ 9,11 steroids from either 11-α- or 11-β-hydroxy steroids, and cannalso be used for the one-step conversion of 11,21-dihydroxynsteroids to 21-chloro-Δ 9,11 steroids. Also disclosed are processesnfor the regioselective conversion of 11-β-chloro steroids to Δ 9,11 nsteroids, and for regioselectively converting an 11,17,21-trihydroxynsteroid to a 21-chloro-11,17-dihydroxy steroid. |