| 摘要 |
PCT No. PCT/EP96/03374 Sec. 371 Date Mar. 27, 1998 Sec. 102(e) Date Mar. 27, 1998 PCT Filed Aug. 1, 1996 PCT Pub. No. WO97/06174 PCT Pub. Date Feb. 20, 1997A process for the preparation of a compound (I) wherein R is a hydroxyl protecting group which comprises isomerising a compound of formula (I) wherein R is a hydroxyl protecting group by reacting the compound of formula (I) with a sterically hindered organic base in the presence of a Lewis acid and a compound of forumula (III) wherein R1 and R2 each independently represent cyano, COR5 or COR2R6 or R1 and R2 together with the carbon atom to which they are attached from a C=O group; R5 represents alkyl, cycloalkyl, amino, alkylamino, dialkyl amino or optionally substituted phenyl or phenylalkyl group; R6 represents alkyl, cycloalkyl or optionally substituted phenyl or phenylalkyl group; R3 and R4 represent each independently hydrogen, alkyl, alkoxy or optionally substituted phenyl group. |
