作者:Peter Scheiner、Sara Arwin、Manes Eliacin、James Tu
DOI:10.1002/jhet.5570220563
日期:1985.9
1-Aminohypoxanthine (1a), a new positional isomer of guanine, has been obtained from 5-aminoimidazole-4-carboxylic acid hydrazide and triethyl orthoformate. Pyrazolo 11 and triazolo 21 analogues of 1 result from similar reactions of the corresponding o-aminoazole hydrazides. An indirect synthesis involving excess ortho-ester and hydrolysis of the resulting intermediate 6 was found most effective for
Synthesis of 5-amino-4, 5-dihydropyrazolo [3,4-d] pyrimidin-4-ones and related isomeric systems
作者:A. Maquestiau、J.-J. Vanden Eynde
DOI:10.1016/s0040-4020(01)83459-1
日期:1987.1
Reactions between aminopyrazole-4-carboxylic acids derivatives and orthoesters or amide acetals lead, in most cases, to the introduction of a heteroalkylidene moiety on the amino group of ethyl aminopyrazole-4-carboxylates and on the β-hydrazide nitrogen atom of aminopyrazole-4-carboxhydrazides.