Carbamimidic acid, methyl ester, sulfate (1:1) → HCID 178498445, compound

Participants

Reaction Conditions

Reaction Steps

A mixture of methyl 2-{(4-nitrophen-yl)methylene}-3-oxobutyrate (12.46 g, 0.05 mol), O-methylisourea hydrogen sulfate (10.32 g, 0.06 mol), and NaOAc (9.84 g, 0.06 mol) in DMF (50 mL) was stirred and heated at 70-75° C. for 4 hours. The mixture was cooled and poured into ice-water (300 mL). The precipitate formed was filtered, washed with water, and dried. The crude product was purified by flash column chromatography on silica gel using 10% through 30% EtOAc in hexane as the gradient eluent (9.8 g, 64%). The 1H-NMR analysis of the product showed it to be a 19:1 mixture of the amine/imine tautomers which was used as such in the next step. 1H-NMR (CDCl3): δ 2.32, 2.38 (2 s, 3H), 3.59, 3.70 (2 s, 3H), 3.70, 3.85 (2 s, 3H), 5.40, 5.66 (s, d, J=3 Hz, 1H), 5.50, 6.08 (s, d, J=3 Hz, 1H), 7.43, 7.45 (2 d, J=9 Hz, 2H), 8.10, 8.11 (2 d, J=9 Hz, 2H).

Provenance & Evidence