Proton sponge → 3-(3-Methoxy-propoxy)-5-(2-oxo-pyrrolidin-1-yl)-benzoic acid methyl ester

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Reaction Steps

3-(3-Hydroxy-propoxy)-5-(2-oxo-pyrrolidin-1-yl)-benzoic acid methyl ester (B15) (127 mg, 0.43 mmol, 1 equiv) in CH2Cl2 (2 ml) was treated with proton sponge (279 mg, 1.30 mmol, 3 equiv) and trimethyloxonium tetrafluoroborate (192 mg, 1.30 mmol, 3 equiv). After 3 hrs, further quantities of proton sponge (93 mg, 0.43 mmol, 1 equiv) and trimethyloxonium tetrafluoroborate (65 mg, 0.43 mmol, 1 equiv) were added and stirring was continued for a further 2 h. The mixture was then partitioned between AcOEt and 2N aqueous HCl solution. The two layers were separated and the aqueous phase extracted with AcOEt. The combined organic layers were washed with saturated aqueous NaHCO3 solution, 2N aqueous HCl solution and brine and then dried over Na2SO4 and concentrated in vacuo. Purification by flash chromatography on silica gel (ethyl acetate/iso-hexane: 1/4 to 1/3) gave 3-(3-methoxy-propoxy)-5-(2-oxo-pyrrolidin-1-yl)-benzoic acid methyl ester (B17) (76 mg, 58%). [M+H]+=308.1

Provenance & Evidence