| 摘要 |
A process for preparing compounds of formula (B) wherein: one of A1' or A2' represents hydrogen and the other represents a group CF3-Y- wherein Y represents -CF2-, > C=O, or -CH(OH)-, or A1' and A2' are groups convertible to A1 and A2 respectively. Y1 represents -O-, -CH2- or NR<O> wherein R<O> is hydrogen, alkyl or alkylcarbonyl; R1 and R2 independently represent hydrogen or alkyl; or R1 and R2 together represent a C2-7 polymethylene moiety; R3 represents hydrogen, hydroxy, alkoxy or acyloxy and R4 is hydrogen or R3 and R4 together represent a bond; which process comprises reacting a compound of formula (C): wherein the variable A1', A2', Y1, R1 and R2 are as defined above, in the presence of an oxygen source and a chiral catalyst as defined in WO/91/14694. |
