Synthesis of 3‐aminopyrazolo[3,4‐ d ]pyrimidine derivatives using N ‐bis(methylthio)methylene‐ p ‐toluenesulfonamide

N ‐Bis(methylthio)methylene‐ p ‐toluenesulfonamide ( 1 ) reacted with active methylene compounds such as malononitrile ( 2a ) and, cyanoacetamide ( 2b ) to give the corresponding 3‐methylthio‐3‐ p ‐toluenesulfonylami‐nopropenenitrile derivatives 3a,b which were found to be convenient starting materials for the synthesis of 3,5‐diaminopyrazole derivatives. Reaction of 3a and 3b with hydrazines gave the corresponding 3,5‐diaminopyrazoles 4a‐e , key intermediates for the synthesis of 3‐aminopyrazolo[3,4‐ d ]pyrimidine derivatives 5a‐d .