Acetic Anhydride → HCID 10449849, compound

Participants

Reaction Steps

A solution of 3-(5-cyclopropyl-1,2,4-oxadiazol-3-yl)-6-fluoro-4,5-dihydroimidazo[1,5-a]quinoxaline (XXXIII, EXAMPLE 103, 0.504 g), dimethylaminopyridine (0.03 g) and acetic anhydride (12 ml) is stirred at 100° for 1 hr. After cooling, excess acetic anhydride is removed under reduced pressure and the residue is partitioned between dichloromethane and aqueous sodium bicarbonate. The phases are separated and the organic phase is dried over sodium sulfate and concentrated. Chromatography on silica gel (320 ml) eluting with methanol/dichloromethane (2/98) gives a poor separation of the product from the imine byproduct. The imine impurity is successfully removed by taking up the mixture in dichloromethane and allowing the imine to precipitate out. The filtrate is collected, concentrated and the product crystallized from dichloromethane and hexane to give the title compound, mp 208.5°-210.0°; MS m/z at 339; IR (mineral oil) 1671, 1503, 1254, 879 and 1204 cm-1 ; NMR (CDCl3) 1.28, 2.38, 2.13, 2.29, 7.16, 7.41 and 8.13 δ.

Provenance & Evidence