CHEMICAL AND ELECTROCHEMICAL REDUCTION OF SOME PYRAZOLO[1,5-A]PYRIMIDINES

Various pyrazolo[1,5-a]pyrimidines 1 are prepared by two different way s. 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 tetra hydrofuran. A complex mixture of oxidizable hydrodimers is obtained by electrochemical reduction. An electroreduction at a more negative pot ential 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- 1H-pyrazole with acetophenone.