Citric Acid → HCID 21866473, compound

Participants

Reaction Conditions

Reaction Steps

112 ml (179 mmol) of a 1.6-molar solution of n-butyllithium in n-hexane were added in the course of 20 minutes to a solution of 25.1 ml (179 mmol) of diisopropylamine in 400 ml of tetrahydrofuran cooled to −78° C. The solution was allowed to come to −35° C., then cooled again to −78° C., and a solution of 20.0 g (162 mmol) of 2-cyano-3-methylthiophene in 80 ml of tetrahydrofuran was slowly added dropwise at this temperature. During this process, the color of the solution changed to dark red. Stirring was continued for 45 minutes, 63 ml (811 mmol) of dimethylformamide were slowly added dropwise, and the mixture was stirred for another 30 minutes. For work-up, a solution of 27 g of citric acid in 160 ml of water was added at −70° C. The mixture was concentrated on a rotary evaporator, 540 ml of saturated sodium chloride solution were added, and the batch was extracted three times using in each case 250 ml of diethyl ether. The combined organic extracts were dried over magnesium sulfate. After the desiccant had been filtered off, the solvent was distilled off under a water pump vacuum and the residue was purified by column chromatography (eluant hexane/ethyl acetate 4/1). This gave 23 g (94%) of the title compound. 1H NMR (270 MHz, DMSO-d6): δ=2.4 (s, 3H), 8.0 (s, 1H), 9.8 (s, 1H).

Provenance & Evidence