Water → 3,4-Bis(phenylthio)-2,5-di(2-thienyl)-tetrahydrofuran

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Reaction Steps

To a suspension of 2,3-bis(phenylthio)-1,4-di(2-thienyl)-1,4-butanediol (54.0 g, 114.9 mmol) in 350 ml dioxane there is added 8.70 g conc. sulfuric acid in 4 almost equal portions with a 45 minutes interval between each addition. The rather thick suspension is stirred mechanically for 4 days at room temperature whereby a clear solution is obtained. The solution is poured into 500 ml water and the product is extracted with 2×300 ml toluene. The organic layer is washed with 2×250 ml water, then dried and rotary evaporated. A quantity of 50 ml ether, followed by 200 ml methanol as well as some seed crystals are stirred into the residue. The crystallized product is filtered off and washed with methanol. It weighs 21.83 g. The filtrate is rotary evaporated and the residue is chromatographed on an aluminum oxide column (16×3 cm) using a 1/1 mixture of toluene and hexane as the eluent, thus obtaining a fraction with an additional amount of the product. This fraction is rotary evaporated and the residue is dissolved in some ether. Methanol is added while stirring, whereupon 3,4-bis(phenylthio)-2,5-di(2-thienyl)-tetrahydrofuran crystallizes. It is isolated in the usual way and weighs 7.04 g. The total yield is 28.87 g (63.9 mmol, 56%).

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