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.
Synthesis of 3-Aminopyrazolo(3,4-d)pyrimidine Derivatives Using N-Bis( methylthio)methylene-p-toluenesulfonamide.-The new ketene N,S-acetals (III) are employed for the synthesis of pyrazoles (V), which can be further converted to several pyrazolopyrimidines such as (VII), (VIII) and (XI). -(TOMINAGA, Y.; HARA, M.; HONKAWA, H.; HOSOMI, A.; J.
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