| 摘要 |
<p>1376123 #<SP>11</SP>-Enolates; 12-halosteroids RESEARCH INSTITUTE FOR MEDICINE & CHEMISTRY Inc 15 Nov 1971 [17 Nov 1970] 54671/70 Heading C2U The invention comprises (A) a process for the 11,12-enolization of a 9α-halo-11-oxosteroid having at least one 12-hydrogen atom, by treating it in a polar aprotic medium with a strong base; (B) a solution of a 9α-halosteroid- 11,12-enolate in a polar aprotic solvent; and (C) 9α,12,12-trifluoro-11-oxo and -11-hydroxysteroids. Thus a 9α-halo-11-oxo-12-unsubstituted steroid is converted by process (A) to a Na, K, Li or Mg enolate (the Li enolate being obtainable either directly with Buhi, or by treating an initially obtained Na enolate with LiCl, or by treating a corresponding enol ester with a lithium base). The enolate may be converted to (i) an enol ester by reaction with an acid derivative, e.g. benzoic anhydride; or (ii) an enol silyl ether by reaction, e.g. with Me 3 SiCl; or (iii) a 9α,12-dihalo-11-oxo steroid by reaction with Cl 2 , Br 2 , ClO 3 F or FOCF 3 . The 9α,12-dihalo-11-oxo steroid may be converted to (i) the corresponding 11-ol by reaction with, e.g. NaBH 4 ; or (ii) an enolate by process (A). The enolate may be acidified to give the 12-epimer of the initial 9α,12-dihalo- 11-oxo steroid, or may be converted by methods analogous to those described above to (i) an enol ester; or (ii) an enol silyl ether; or (iii) a 9α-halo-12,12-difluoro-11-oxo steroid. The latter may be reduced to the corresponding 11-ol and any protecting groups (e.g. 3-ketal, 3-enol ether and 17,20;20,21-bismethylenedioxy) removed. In the examples the starting materials for the above conversions are protected derivatives of 9α-fluorocortisone and 9α-fluoro-16α-methylprednisone.</p> |
