Sulfuric Acid → (E)-6-(4-chlorophenyl)-2,4-dioxo-hex-5-enoic acid methyl ester

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Reaction Steps

A solution of (E)-6-(4-chlorophenyl)-2,4-dioxo-hex-5-enoic acid ethyl ester (4; 33.39 g, 0.12 mol) and conc H2SO4 (0.5 mL) was stirred at reflux for 6 h in methyl alcohol (MeOH, 400 mL). Upon cooling and solvent concentration, (E)-6-(4-chlorophenyl)-2,4-dioxo-hex-5-enoic acid methyl ester (6; 22.7 g, 71%) was collected as yellow crystals: mp 135-136° C.; 1H NMR (400 MHz, CDCl3) δ 14.74 (s, 1H), 7.67 (d, J=15.9 Hz, 1H), 7.49 (d, J=8.5 Hz, 2H), 7.38 (d, J=8.5 Hz, 2H), 6.61 (d, J=15.9 Hz, 1H), 6.53 (s, 1H), 3.92 (s, 3H); HRMS-ESI (m/z): calcd for C13H11ClO4, 266.034. found, 266.034.

Provenance & Evidence