Process for the preparation of 2-amino-6-chlorine purine famciclovi and process for the preparation of 2-amino-6-chlorine purine penciclovi

摘要

A process for the preparation of a compound of formula (A) wherein: X is hydrogen or hydroxy, chloro, CSUB1-6 /SUBalkoxy or pheny CSUB1-6 /SUBalkoxy; and RSUBa /SUBand RSUBb /SUBare hydrogen, or acyl or phosphate derivatives thereof, which process comprises: (i) the preparation of a compound of formula (I) wherein RSUB1 /SUBis CSUB1-6 /SUBalkyl, or phenyl CSUB1-6 /SUBalkyl in which the phenyl group is optionally substituted; RSUB2 /SUBis hydrogen, hydroxy, chlorine, CSUB1-6 /SUBalkoxy, phenyl CSUB1-6 /SUBalkoxy or amino; and RSUB3 /SUBis halogen, CSUB1-6 /SUBalkylthio, CSUB1-6 /SUBalkylsulphonyl, azido, an amino group or a protected amino group, which preparation comprises the reaction of a compound of formula (II) wherein RSUB2 /SUBand RSUB3 /SUBare as defined for formula (I) with a compound of formula (V) wherein L is a leaving group and RSUB1 /SUBis 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 RSUB1/SUB, RSUB2 /SUBand RSUB3 /SUBto further values of RSUB1/SUB, RSUB2 /SUBand RSUB3/SUB; (ii) the conversion of the resulting compound of formula (I) to a compound of formula (A) by converting variable RSUB3/SUB, when other than amino, to amino, reducing the ester groups COSUB2/SUBRSUB1 /SUBto CHSUB2/SUBOH and optionally forming acyl or phosphate derivates thereof, and as necessary or desired converting variable RSUB2 /SUBin the compound of formula (I) to variable X in the compound of formula (A); characterized in that RSUB2 /SUBis chloro in formula (I)