Dimethylformamide → alpha-Chloro-2-nitrobenzenepropanoic acid 2,6-dimethylpiperidine salt

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Reaction Conditions

Reaction Steps

To magnetically stirred N,N-dimethylformamide (2 ml, 25.8 mmol) cooled in ice was added slowly dropwise thionyl chloride (3 ml, 41.1 mmol), and the resulting cold Vilsmeier reagent was diluted with dichloromethane (10 ml). α-Hydroxy-2-nitrobenzenepropanoic acid (2.00 g, 9.47 mmol), followed by an additional 2 ml of dichloromethane was added. The mixture, protected from moisture, was stirred at room temperature (25° C.) overnight. The resulting solution was evaporated to a syrup. The syrup was dissolved in dichloromethane and the solution was added to stirred ice. The mixture was stirred for 1 hour during which time it warmed to room temperature. The dichloromethane solution was separated and washed (X4) with water and dried (MgSO4). Evaporation gave a syrup which was subjected to an oil pump vacuum for half an hour. The syrup was dissolved in ether and 2,6-dimethylpiperidine was added to approximate neutrality (pH 9 with pH paper). The crude titled product [2.36 g (81%), mp 138-140° C.]crystallized readily. Recrystallization (methanol-ether) with decolorization (Nuchar C-190N) gave pure product, mp 141°-143° C.

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