Boron trifluoride etherate → Methyl 3-[2,4-dimethoxy-5-(1,3-dithian-2-yl)phenyl]octanoate

Participants

Reaction Steps

150 mg (1.39 mmol) of 1,3-propanedithiol, 1.0 g of magnesium sulfate and a catalytic amount of boron trifluoride etherate were added, with ice-cooling, to a solution of 447 mg (1.39 mmol) of methyl 3-(2,4-dimetlioxy-5-formylphenyl)octanoate [prepared as described in Preparation 32(ii)] in 12 ml of methylene chloride, and the resulting mixture was stirred at the same temperature for 2 hours. At the end of this time, the reaction mixture was neutralized with a saturated aqueous solution of sodium hydrogencarbonate, and then the dehydrating agent was removed by filtration using a Celite (trade mark) filter aid. The filtrate was concentrated by evaporation under reduced pressure, and the concentrate was extracted with ethyl acetate. The extract was washed with water and with a saturated aqueous solution of sodium chloride, in that order, after which it was dried over anhydrous sodium sulfate. The solvent was removed by distillation under reduced pressure, and the resulting residue was purified by column chromatography through 10 g of silica gel, using a 5:1 by volume mixture of hexane and ethyl acetate as the eluent, to give 589 mg (a quantitative yield) of the 1,3-dithiane derivative as an oily substance.

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