Facile synthesis of 1-substituted 4,5-diaminopyrazoles and its application toward the synthesis of pyrazolo[3,4- b ]pyrazines
作者:Tun-Cheng Chien、Ronald A. Smaldone、Leroy B. Townsend
DOI:10.1016/j.tetlet.2004.03.142
日期:2004.5
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 condensed with glyoxal to afford 1-substituted pyrazolo[3,4-b]pyrazines.
由适当的5-氨基吡唑-4-羧酸酯制备1-取代的5-氨基吡唑-4-羰基叠氮化物。酰基叠氮化物经历Curtius重排,然后用醇淬灭以形成相应的氨基甲酸酯。通过催化氢解解封1-取代的5-氨基-4-苄氧基羰基氨基吡唑,得到所需的4,5-二氨基吡唑。立即将这些4,5-二氨基吡唑与乙二醛缩合,得到1-取代的吡唑并[3,4- b ]吡嗪。