Ethyl levulinate → 1H-Pyrrolo(1,2-a)imidazole-2,5(3H,6H)-dione, dihydro-7a-methyl-

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Reaction Steps

To a solution of glycinamide hydrochloride (18.4 g, 0.166 mol) in water (200 ml), adjusted to pH 9.5 with 10% sodium hydroxide (about 60 ml), ethyl 4-oxopentanoate (20 g, 0.139 mol) was added. The solution was refluxed for 24 hours. After cooling the solvent was evaporated under vacuum and the residue was chromatographed over silica gel (dichloromethane-methanol 9:1) to afford 4.5 g (21%) of the title compound, m.p. 187°-189° C. NMR (CDCl3): deltaH =4.17 and 3.53 (ABq, J=16 Hz, 2H, NCH2CO), 1.5 (s, 3H, CH3). MS (E.I., 70 eV, 1.5 mA) m/z=154 (M+), 139 (M--CH3)+, 111 (M--CONH)+.

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