摘要 |
<p>A process for the preparation of a compound of formula (A) wherein: X is hydrogen or hydroxy, chloro, C<SUB>1-6 </SUB>alkoxy or pheny C<SUB>1-6 </SUB>alkoxy; and R<SUB>a </SUB>and R<SUB>b </SUB>are hydrogen, or acyl or phosphate derivatives thereof, which process comprises: (i) the preparation of a compound of formula (I) wherein R<SUB>1 </SUB>is C<SUB>1-6 </SUB>alkyl, or phenyl C<SUB>1-6 </SUB>alkyl in which the phenyl group is optionally substituted; R<SUB>2 </SUB>is hydrogen, hydroxy, chlorine, C<SUB>1-6 </SUB>alkoxy, phenyl C<SUB>1-6 </SUB>alkoxy or amino; and R<SUB>3 </SUB>is halogen, C<SUB>1-6 </SUB>alkylthio, C<SUB>1-6 </SUB>alkylsulphonyl, azido, an amino group or a protected amino group, which preparation comprises the reaction of a compound of formula (II) wherein R<SUB>2 </SUB>and R<SUB>3 </SUB>are as defined for formula (I) with a compound of formula (V) wherein L is a leaving group and R<SUB>1 </SUB>is as defined for formula (I), to give a compound of formula (VI), and thereafter converting the intermediate compound of formula (VI) to a compound of formula (I) via decarboxylation, and as necessary or desired, interconverting variables R<SUB>1</SUB>, R<SUB>2 </SUB>and R<SUB>3 </SUB>to further values of R<SUB>1</SUB>, R<SUB>2 </SUB>and R<SUB>3</SUB>; (ii) the conversion of the resulting compound of formula (I) to a compound of formula (A) by converting variable R<SUB>3</SUB>, when other than amino, to amino, reducing the ester groups CO<SUB>2</SUB>R<SUB>1 </SUB>to CH<SUB>2</SUB>OH and optionally forming acyl or phosphate derivates thereof, and as necessary or desired converting variable R<SUB>2 </SUB>in the compound of formula (I) to variable X in the compound of formula (A); characterized in that R<SUB>2 </SUB>is chloro in formula (I)</p> |