HCID 13282157, compound → HCID 70520957, compound

Participants

Reaction Steps

A suspension of 2-methyl-2H-benzofuro[3,2-c]pyrazol-3-amine (3.8 g, 20 mmol, described in Example 6) in triethyl orthoformate (40 mL) was refluxed with stirring for 4 hr. The excess solvent was removed under vacuum and the residue was triturated with diethyl ether to give 4.5 g of N-ethoxymethylene-2-methyl-2H-benzofuro[3,2-c]pyrazol-3-amine, mp 120°-122° C., and NMR (CDCl3) δ1.4 (3H, t), 3.95 (3H, s), 4.4 (2H, q), 7.5 (4H, m) and 8.5 (1H, s). The latter compound was suspended in ethanol (100 mL) and sodium borohydride (1 g, 26 mmol) was added in portions. The mixture was stirred at room temperature for 1 hr and at reflux temperature for 0.5 hr. The solution was evaporated to dryness and the residue was taken up in ethyl acetate. The solution was washed with water, dried and evaporated to dryness. Chromatography on silica gel and elution with 2% EtOH--CH2Cl2 (v/v) gave 2.5 g of crystalline product, mp 150°-156° C. The latter product was triturated with diethyl ether to obtain the title compound: mp 154°-156° C.; IR (mineral oil) 3190, 1640, 1600 and 1547 cm-1 ; UV max (MeOH) 301 nm (ε=4820), 271 (14800), 251 (18900), 212 (20090) and shoulder 246; NMR (DMSO-d6) δ2.97 (3H, d), 3.68 (3H, s), 5.51 (1H, q) and 7.0-8.0 (4H, m).

Provenance & Evidence