A short synthesis of 4-substituted 1-(hydroxyalkyl)-1H-pyrazolo[3,4-d]pyrimidines

Abstract

A simple and practical procedure was developed for the preparation of 4-substituted-1-(hydroxyalkyl)-1H-pyrazolo[3,4-d]pyrimidines. This was achieved by reacting nucleobase 3a or 3b with cesium carbonate or DBU in the presence of various alkyl iodides at 0°C in DMF. This procedure appears to be of general utility, proceeds in reasonable yield, and is applicable to different alkyl chain lengths including protected and unprotected alcohols. The synthetic utility of this approach is demonstrated by the facile synthesis of ST 689, a potent immunostimulatory drug.