Propargyl alcohol → Tetrahydro-2-(2-propynyloxy)-2H-pyran

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of 112 g (2.0 mol.) of 3-hydroxy-1-propyne and 260 g (3.0 mol.) of dihydropyran in 1.20 liters of methylene chloride cooled to 0° C. in an ice bath, is added a solution of 20 mg of para-toluenesulfonic acid in 100 ml of methylene chloride, dropwise. The reaction mixture is stirred at 0° C. for one-half hour, and at ambient temperature for one hour. It is then poured into 200 ml of a 5solution of sodium bicarbonate, the organic phase is separated, the aqueousphase extracted with 100 ml of methylene chloride, the combined organic phases washed with 100 ml of a solution of brine, dried over sodium sulfate, and evaporated under vacuum (12 mm) at 45° C. to give 300 g of crude product, which is purified by fractional distillation, bp 71°-73° C. (14 mm) to yield 250 g (89%) of a liquid.

Provenance & Evidence