2-Chloro-4-nitrobenzoic acid → 2-(1,3-Dimethoxy-1,3-dioxopropan-2-yl)-4-nitrobenzoic acid

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Reaction Conditions

Reaction Steps

A solution of 2-chloro-4-nitrobenzoic acid (75 g, 372 mmol) in dimethyl malonate (900 mL, 20 equivalents) was degassed with nitrogen for 15 min. Copper (I) bromide (5.4 g, 37 mmol) was added in one portion. Sodium methoxide (48.3 g, 894 mmol) was added in one portion to the solution while stirring and the contents exothermed to 48° C. Fifteen minutes later, the contents were heated to 70° C. for 24 hrs. The reaction was complete by nmr. Water (900 mL) was added to the cooled reaction followed by hexanes (900 mL). The aqueous layer was separated, toluene (900 mL) added, the solution filtered through Celite®, and the aqueous layer separated. Fresh toluene (1800 mL) was added to the aqueous layer and the biphasic mixture acidified with 6 N aqueous HCl (90 mL). A white precipitate formed and the contents were stirred for 18 hrs. The product was filtered off and dried to give a white solid, 78.1 g (70%, mp 153° C.). IR 2923, 2853, 1750, 1728, 1705, 1458, 1376, 1352, 1305, 1261 cm-1.1H NMR (CD3)2SO δ8.37(d,J=2 Hz, 1H), 8.30 (d,J=1 Hz,2H), 5.82(s, 1H),3.83 (s,6H).13C NMR (CD3)2SOδ168.0, 167.3, 149.4, 137.1, 135.8, 132.5, 125.4, 123.7, 54.5, 53.4.Anal. Calcd for C11H10NO8 :C,48.49; H,3.73; N, 4.71. Found:C, 48.27; H,3.72; N, 4.76.

Provenance & Evidence