Process for preparing purine derivatives

Abstract

The present invention relates to a process for preparing a compound of formula [I], said process comprising the steps of: formula [II]+formula [III]→formula [I] (i) forming a reaction mixture comprising (a) a compound of formula [II], (b) a compound of formula [III] and (c) 1,2-propanediol or polyethylene glycol, or a mixture thereof, and optionally (d) a base; (ii) heating said reaction mixture to a temperature of at least about 150° C. to form a compound of formula [I]; (iii) isolating said compound of formula [I]; and (iv) optionally converting said compound of formula [I] into salt form; wherein: Rand Rare each independently H, alkyl or haloalkyl; Rand Rare each independently H, alkyl, haloalkyl or aryl; Ris alkyl, alkenyl, cycloalkyl or cycloalkyl-alkyl, each of which may be optionally substituted with one or more OH groups; Ris selected from cyclopropylamino, cyclopropylmethylamino, cyclobutylamino, cyclobutylmethylamino and formula (A) where one of X, Y and Z is N and the remainder are CR; R, Rand each Rare independently H, alkyl or haloalkyl, wherein at least one of R, Rand Ris other than H. Further aspects of the invention relate to a highly diastereoselective process for the preparation of compounds of formula [III], a process for preparing intermediates of formula [II], and other intermediates useful in the synthesis of compounds of formula [I], and to a process for preparing the crystalline tartrate salt and free base of compounds of formula [I].