2,2-Dimethoxypropane → 2-(2,2-dimethyl-1,3-dioxolan-4-yl)-7,8-dihydroquinolin-5(6H)-one

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Reaction Steps

A mixture of 2-(1,2-dihydroxyethyl)-7,8-dihydroquinolin-5(6H)-one (Preparation 54D, 0.226 g, 1.09 mmol), 2,2-dimethoxypropane (0.402 mL, 3.27 mmol), and (1R)-(−)-camphorsulfonic acid (0.051 g, 0.22 mmol) in acetone (6 mL) was stirred at room temperature overnight. The reaction mixture was quenched with a saturated aqueous solution of sodium bicarbonate and concentrated under reduced pressure. The aqueous residue was diluted with ethyl acetate, washed with a saturated aqueous solution of sodium bicarbonate and brine. The organic layer was collected, and the aqueous layer was extracted with ethyl acetate. The combined organic layers were dried over anhydrous sodium sulfate and concentrated and purified by flash silica gel chromatography using a mixture of ethyl acetate in hexane (50%) to afford 2-(2,2-dimethyl-1,3-dioxolan-4-yl)-7,8-dihydroquinolin-5(6H)-one (0.182 g, 0.736 mmol, 68% yield) as a clear, colorless oil. The product had an HPLC ret. time=1.75 min. (condition A); LC/MS M+1=247.9.

Provenance & Evidence