Methyl acetoacetate → 4-[1-(Cyclohexylmethyl-amino)-ethylidene]-pent-2-enedioic acid dimethyl ester

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Reaction Steps

A mixture of cyclohexanemethylamine (3 g, 26.5 mmol) and 3-oxo-butyric acid methyl ester (3.5 mL, 31.8 mmol) in MeOH (100 mL) was refluxed for 2 h. Propynoic acid methyl ester (3.6 mL, 39.8 mmol) was added, and the resulting mixture was refluxed for 2 days. After cooling to r.t., the solvent was evaporated, and the crude oil was recrystallized from MeOH to give 6.3 g of the title compound as a light tan solid. 1H NMR (CDCl3, 200 MHz): δ=10.73 (br s, 1H), 7.76 (d, 1H, J=15.4 Hz), 6.06 (d, 1H, J=15.4 Hz), 3.77 (s, 3H), 3.72 (s, 3H), 3.18 (t, 2H, J=6.2 Hz), 2.25 (s, 3H), 0.80-1.90 (m, 11H).

Provenance & Evidence