UNFORESEEN ALKYLATING EFFECT OF TRIETHYLORTHOFORMATE IN THE SYNTHESISOF PYRAZOLOTRIAZOLOPYRIMIDINE DERIVATIVES

The final ring closure reaction of 2-phenylamino-3-aminopyrazolo [3,4- d]pyrimidin-4-ones with triethylorthoformate in the synthesis of ,4-d] [1,2,4]-8H-triazolo[2,3-a]-4H-pyrimidin-4-one derivatives, unexpectedl y gave both the desired product and its N-2-ethyl analog. The structur e of the latter, which arises from an unexpected alkylating effect of triethylorthoformate, was determined through a combined instrumental m ass spectroscopy/NMR study reported elsewhere (S Pucci et al, manuscri pt in preparation). It was further defined using a comparison between a sample of 4 obtained by synthesis and a sample of 4 isolated by PLC or RP-PLC of the crude reaction product.