Phenol → Phenyl 4,5-Dihydro-5-[(pyrrolidino)carbonyl]imidazo[1,5-a]quinoxaline-3-carboxylate

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Reaction Steps

To a mixture of 4,5-dihydro-5-[(pyrrolidino)carbonyl]imidazo[1,5-a]quinoxaline-3-carboxylic acid (I, EXAMPLE 323, 0.543 g), 0.245 g of phenol, 0.48 ml of triethylamine, and 6 ml of dichloromethane are added 0.42 ml of diethyl cyanophosphonate. After stirring for 1 hr an additional 0.11 g of phenol are added. When the reaction had stirred another 2.5 hr an additional 0.11 g of phenol and 0.26 ml of diethyl cyanophosphonate are added. The reaction is stored overnight in the refrigerator and then stirred with 1 ml of aqueous sodium bicarbonate for about 30 min. The mixture is then partitioned between dichloromethane and aqueous sodium bicarbonate. The organic layers are dried over sodium sulfate, concentrated, and the residue chromatographed on silica gel (300 ml) eluting with methanol/methylene chloride (2/98), the appropriate fractions are pooled and concentrated to give the title compound, which is crystallized from dichloromethane/hexane, mp 196.5°-199°; MS (m/z) at 388; IR (mineral oil) 1648, 1199, 1723, 1502, 1410 cm-1 ; 1H NMR (CDCl3) 1.81, 3.31, 5.09, 7.15-7.33, 7.42, 7.55, 8.11 δ.

Provenance & Evidence