Formamide → 1,2-dihydropyrazolo[4,3-g]quinazolin-5-one

Participants

Reaction Steps

450 mg (2.5 m-mol) of 6-amino-indazole-5-carboxylic acid (formula 20, prepared according to Example XIII) in 3 ml of formamide were heat-melted and kept at a temperature of 140° during a period of 4.5 hours and then at a temperature of 180° during another period of 1.5 hours. The mass obtained was cooled to room temperature. The product was filtered under suction, washed well with water until the filtrate became clear, and then washed with a small amount of ethanol. The target product (formula 3) was recovered in an amount of 167 mg (36%) in the form of a greyish-brown, finely crystalline material, m.p. 330°. The product was uniform as evidenced by chromatography; pmr (DMSO-d6): δ 7.78, 8.10, 8.44, 8.76 (4 broad s, 4, H3, H4, H7, H9), 11.92, 13.36 (2 with D2O exchangeable broad m, 2, N1H, N6H), (DMSO-d 6 /D2O): δ 7.83, 8.10, 8.45, 8.78 (4 sharp s, 4, H3, H4, H7, H9); ms (70 eV): m/e 186 (100%, M+).

Provenance & Evidence