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Chemical and electrochemical reduction of some pyrazolo[1,5‐ a ]pyrimidines
Author(s) -
Bellec Christian,
Lhommet GÉRard
Publication year - 1995
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570320621
Subject(s) - chemistry , acetophenone , sodium borohydride , electrochemistry , tetrahydrofuran , lithium (medication) , pyrimidine , aluminum hydride , condensation , borohydride , pyrazole , inorganic chemistry , organic chemistry , medicinal chemistry , stereochemistry , methanol , electrode , medicine , physics , methoxide , solvent , thermodynamics , endocrinology , catalysis
Abstract Various pyrazolo[1,5‐ a ]pyrimidines 1 are prepared by two different ways. Their chemical reduction by sodium borohydride leads generally to 4,5,6,7‐tetrahydro compounds 3, while lithium aluminum hydride yields 4,7‐dihydro derivatives 2 at room temperature, and 3 in refluxing tetrahydrofuran. A complex mixture of oxidizable hydrodimers is obtained by electrochemical reduction. An electroreduction at a more negative potential also gives 4,7‐dihydro compounds 2. A new 4,5‐dihydropyrazolo[1,5‐ a ]pyrimidine has been obtained by condensation of 5‐amino‐3‐methyl‐1 H ‐pyrazole with acetophenone.