Phosgene → 3-(5-Cyclopropyl-1,2,4-oxadiazol-3-yl)-4,5-dihydro-5-[(morpholino)carbonyl]imidazo[1,5-a]quinoxaline

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Reaction Steps

To a slurry consisting of 3-(5-cyclopropyl-1,2,4-oxadiazol-3-yl)-4,5-dihydroimidazo[1,5-a]quinoxaline (XXXIII, EXAMPLE 88, 0.499 g), diisopropylethylamine (0.81 ml) and THF (15 ml) is added phosgene (1.93M in toluene, 1.20 ml). A slight exotherm ensues and the slurry becomes homogeneous. After 10 min, morpholine (0.20 ml) is added. The mixture is stirred for 2 hr and then partitioned between ethyl acetate, water, and saline. The phases are separated and the organic phase is dried over magnesium sulfate and concentrated. The crude product is chromatographed on silica gel (150 ml) eluting with methanol/dichloromethane (2/98). The appropriate fractions are pooled and concentrated to give the product. Recrystallization from dichloromethane and hexane gives the title compound, mp 198.0°-198.5°; MS (m/z) at 392; IR 1662, 1506, 1409, 1277, and 1579 cm-1 ; NMR (CDCl3) 1.24, 1.36, 2.27, 3.33, 3.64, 5.02, 7.21, 7.27, 7.55 and 8.11 δ.

Provenance & Evidence