| abstract |
A process for the preparation of a compound of formula (A):n n wherein X is hydrogen, hydroxy, chloro, C₁₋₆ alkoxy or phenyl C₁₋₆ alkoxy and R a and R b are hydrogen, including acyl and phosphate derivatives thereof; which process comprises: ni) the preparation of a compound of formula (I):n n 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, which process comprises the reaction of a compound of formula (II):n n with a compound of formula (VII):n n wherein Q is a leaving group, J is hydrogen or halo and R₁ is as hereinbefore defined; to give a compound of formula (VIII):n n followed by reduction of the compound of formula (VIII) to give a compound of formula (I) as hereinbefore defined; and, as necessary or desired, interconverting variables R₁, R₂ and R₃ to further values of R₁, R₂ and R₃; n(ii) the conversion of the resulting compound of formula (I) to a compound of formula (A) by converting variable R₃, when other than amino, to amino, reducing the ester groups CO₂R₁ to CH₂OH and optionally forming acyl or phosphate derivatives thereof, and as necessary or desired converting variable R₂ in the compound of formula (I) to variable X in the compound of formula (A). |