1961 年 81 巻 12 号 p. 1738-1742
Pyrazolopyridine derivatives with nitrogen in 6- or 4-position were synthesized. For that with nitrogen in 6-position, 1-phenyl-2-methyl-3-amino-3-pyrazolin-5-one (I) and ethyl acetoacetate (II) were reacted according to the method of Fierz-David, and the cyclized product, 1, 4-dimethyl-2-phenyl-6-hydroxy-1, 2-dihydro-3H-pyrazolo [3, 4-b] pyridin-3-one, was obtained in one step. The anil compound was prepared from (I) and (II) by the Conrad-Limpach reaction and its compound was further cyclized at 250° to afford 1, 6-dimethyl-2-phenyl-4-hydroxy-1, 2-dihydro-3H-pyrazolo [3, 4-b] pyridin-3-one, which was further derived to the true pyrazolo-pyridine compound.
The derivative with nitrogen in 4-position was started from 3-pyrazoline-3-carboxaldehyde derivative and reacted according to Sugasawa's method and ethyl 1, 5-dimethyl-2-phenyl-3-oxo-1, 2-dihydro-3H-pyrazolo [4, 3-b] pyridine-6-carboxylate was identified as its platinum salt.