Methylamine → 3-(3,5-DI-Tert-butyl-4-hydroxyphenyl)-N-methyl-3-oxopropanamide

A 500-mL flask was charged with 3-(3,5-di-tert-butyl-4-hydroxy-phenyl)-3-oxo-propanoic acid methyl ester (24.3 g, 79.3 mmol) and a 40% methylamine solution (55 g). The solution was stirred for 2 h. The conversion of the starting material (Rf 0.91) to the title compound (Rf 0.4) was monitored by TLC using 1:1 ethyl acetate-hexane as solvent and UV detection of the substances. The solution was diluted with 2-propanol (100 mL) and evaporated. The solid residue was taken up in boiling 2-propanol (ca. 100 mL) and evaporated again. The residue was again taken up in boiling toluene (ca. 75 mL) and the hot solution was concentrated to afford a crystalline suspension. This suspension was re-dissolved by heating and the hot solution was diluted with cyclohexane (80 mL) to cause immediate crystallization. The suspension was homogenized by reheating, allowed to cool to room temperature, then refrigerated overnight and filtered. The filter cake washed with cyclohexane and hexane, dried to constant weight at 65° C. and 20 torr to afford 22.77 g of the title compound. This material was recrystallized by dissolving in boiling toluene (ca. 120 mL) followed by the addition of cyclohexane (100 mL). The suspension was allowed to cool to room temperature, then refrigerated and filtered. The filter cake was washed with cyclohexane then hexane and dried to constant weight at 65° C. and 20 torr to afford 22.03 g of the title compound (91%). TLC (1:1 ethyl acetate-hexane) Rf 0.48; 1H-NMR (300 MHz, DMSO-d6) δ 1.37 (9H, s), 2.57 (3H, d, J=4.6 Hz), 3.73 (2H s), 7.73 (2H, s), 7.85 (1H, s), 8.08 (1H, br s).