Pyrazole誘導体の研究 (第10報)

Pyrazolo [1,5-a] pyrimidine誘導体の合成

抄録

Ethyl [(5-pyrazolyl) aminoalkylidene] cyanoacetates were obtained by heating ethyl (1-ethoxyalkylidene) cyanoacetates with 5-aminopyrazoles. In the cyclization reaction of these compounds, ethylidene-(XI-XIII) and propylidene-cyanoacetates (XIV to XV) tended undergo cyclization at the ester group to form 6-cyanopyrazolo [1, 5-a] pyrimidin-7(4H)-one compounds (XXIV to XXIX). When heated with sodium ethoxide catalyst in ethanol, they formed only the 7-one compounds, while heating with hydrochloric acid catalyst gave, besides the 7-one compound, ethyl 7-aminopyrazolo [1, 5-a] pyrimidine-6-carboxylates (XVII to XXII) formed by cyclization at the nitrile group. Methylenecyanoacetates (XVI and XXXII) tended to form the 7-amino compounds by cyclization at the nitrile group. When heated in ethanol with the hydrochloric acid catalyst or a large excess of sodium ethoxide catalyst, 7-amino compounds (XXIII and XXXIII) are almost the only product, while the use of about 2 molar equivalents of sodium ethoxide as a catalyst gives the 7-one compounds (XXX and XXXIV) at the same time. Heating of (1-ethoxyethylidene) malononitrile (IV) and 5-aminopyrazoles (V to VIII) in ethanol without a catalyst results in condensation and cyclization to form 7-aminopyrazolo [1, 5-a] pyrimidine-6-carbonitriles (XXXV to XXXVIII).