Facile Cascade Synthesis of 6‐(Chloromethyl)pyrazolo[3,4‐d]pyrimidines from 5‐Amino‐1H‐pyrazole‐4‐carbaldehydes

Abstract A facile cascade method was developed for synthesis of 6‐(halomethyl)pyrazolo[3,4‐ d ]pyrimidines from 5‐amino‐1 H ‐pyrazole‐4‐carbaldehydes via amidation and sequential heterocyclization in two steps. This synthetic method allowed to prepare 1,3‐disubstituted 6‐(halomethyl)pyrazolo[3,4‐ d ]pyrimidines by using series of 5‐amino‐1 H ‐pyrazole‐4‐carbaldehydes as the starting materials in presence of the commercially available safety agents, including 2‐haloacetyl chloride, trimethylamine, and ammonium hydroxide.