反应详情

A suspension of ethyl 3-hydroxybenzo[b]furan-2-carboximidate hydrochloride (8.86 g 36.7 mmol, described in Example 4) in benzene (400 mL) was combined with freshly prepared acetone hydrazone (8.0 g, 110 mmol). A solution was formed then a precipitate occurred. The mixture was refluxed for 1.5 hr, additional acetone hydrazone (5.0 g, 69 mmol) was added and the solution was refluxed for 0.5 hr. The reaction mixture was filtered hot to remove the precipitate (discarded), the filtrate was evaporated to dryness and the residue was triturated with diethyl ether to give 6.2 g of 3-hydroxybenzo[b]furan-2-carboximidic acid, 2-(2-propanehydrazide), the mp of which, 218°-220° C. (dec.), remained constant on recrystallization from acetonitrile: IR (mineral oil) 3411, 3120, 1640, 1600, 1520, 1450, 1100 and 1190 cm-1 ; NMR (DMSO-d6) δ1.95 (3H, s), 2.00 (3H, s), 7.3 and 7.6 (4 H, m), and ca. 7.6 (2H).

1. customA solution was formed
2. temperatureThe mixture was refluxed for 1.5 hr
3. temperaturethe solution was refluxed for 0.5 hr
4. filtrationThe reaction mixture was filtered hot
5. customto remove the precipitate (discarded)
6. customthe filtrate was evaporated to dryness
7. customthe residue was triturated with diethyl ether