3,4-dihydro-2H-pyran → Tetrahydropyranyl ether

Participants

Reaction Steps

A mixture of 2.65 g of (1R,5S,6R,7R)-6- ethoxycarbonyl-3,3-ethylenedioxy-7-hydroxybicyclo[3.3.0]octane (IX), 1.34 g of dihydropyrane, 0.26 g of pyridinium p-toluenesulfonate in 30 ml of anhydrous methylene chloride was stirred at room temperature for 3 hours. Then, the reaction mixture was successively washed with saturated aqueous sodium hydrogencarbonate solution and saturated brine, dried over sodium sulfate, and concentrated to obtain as the residue 3.70 g of oily tetrahydropyranyl ether. A solution of the resulted crude tetrahydropyranyl ether in 15 ml of anhydrous diethyl ether was added dropwise over 1 hour to a stired and ice-cooled suspension of 0.59 g of lithium aluminum hydride in 50 ml of anhydrous diethyl ether. The mixture was further stirred at room temperature for 30 minutes. After ice-cooling, to the reaction mixture was added successively 0.6 ml of water, 1.8 ml of 10% aqueous sodium hydroxide solution and 0.6 ml of water, and the mixture was further stirred for 1 hour. The mixture was filtered through Celite, dried over sodium sulfate, and concentrated. The residue was purified by silica gel chromatography (eluting solution: 25% (v/v) ethyl acetate/hexane) to obtain 3.04 g of the oily title compound.

Provenance & Evidence