Tetrahedron letters

Facile synthesis of 1-substituted 4, 5-diaminopyrazoles and its application toward the synthesis of pyrazolo [3, 4-b] pyrazines

TC Chien, RA Smaldone, LB Townsend

Index: Chien, Tun-Cheng; Smaldone, Ronald A.; Townsend, Leroy B. Tetrahedron Letters, 2004 , vol. 45, # 21 p. 4105 - 4108

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Citation Number: 10

Abstract

1-Substituted 5-aminopyrazole-4-carbonylazides were prepared from the appropriate 5- aminopyrazole-4-carboxylates. The acyl azides undergo a Curtius rearrangement followed by quenching with alcohols to form the corresponding carbamates. The 1-substituted 5- amino-4-benzyloxycarbonylaminopyrazoles were unblocked by catalytic hydrogenolysis to give the desired 4, 5-diaminopyrazoles. These 4, 5-diaminopyrazoles were immediately ...