| 摘要 |
A process for preparing pharmaceutically active compounds of formula (A): <IMAGE> (A) wherein X is hydrogen, hydroxy, chloro, C1-6 alkoxy or phenyl C1-6 alkoxy; and Ra and Rb are hydrogen, or acyl or phosphate derivatives thereof, which process comprises the preparation of an intermediate of formula (I): <IMAGE> (I) wherein R1 is C1-6 alkyl, or phenyl C1-6 alkyl in which the phenyl group is optionally substituted; R2 is hydrogen, hydroxy, chlorine, C1-6 alkoxy, phenyl C1-6 alkoxy or amino; and R3 is halogen, C1-6 alkylthio, C1-6 alkylsulphonyl, azido, an amino group or a protected amino group, via the reaction of a compound of formula (II): <IMAGE> (II) wherein R2 and R3 are as defined for formula (I) with: (a) a compound of formula (III): <IMAGE> (III) wherein R4 and R5 are independently hydrogen, C1-6 alkyl, or phenyl, or R4 and R5 together are C5-7 cycloalkyl; or (b), a compound of formula (V): <IMAGE> (V) wherein L is a leaving group and R1 is as defined for formula (I), and thereafter converting the resulting intermediates to a compound of formula (I) and converting a compound of formula (I) to a compound of formula (A).
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