Diethyl Ether → 2-[(2-phenylethanethioyl)sulfanyl]succinic Acid

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Reaction Steps

A solution of benzylmagnesium chloride in ether (1.0 M, 200 mL, 0.20 mol) was added to dry tetrahydrofuran (200 mL) under nitrogen. Carbon disulfide (20 mL, 25 g, 0.33 mol) was then added slowly with stirring. After 15 min, fumaric acid (23.2 g, 0.20 mol) was added and the ether was mostly removed by distillation. More tetrahydrofuran (100 mL) was added, and the solution was heated under reflux for 14 h. The reaction was cooled and poured into ether (1 L), then extracted with water (3×100 mL) followed by saturated sodium bicarbonate (5×200 mL). The bicarbonate extracts were combined and extracted with ether (2×100 mL), then acidified slowly to pH<1 with concentrated hydrochloric acid, and extracted with ethyl acetate (3×200 mL). The combined organic layers were washed with water (200 mL) and saturated sodium chloride (100 mL), and then evaporated. The crude mixture was crystallized by trituration with 50:50 ether/light petroleum (100 mL). The solid was collected and placed in water (150 mL) at 65° whereupon most of the solid dissolved. The mixture was then quickly cooled in an ice bath and the resulting crystals were collected and washed with cold water (3×33 mL). The solid was then dissolved in a mixture of water (150 mL), ethyl acetate (600 mL) and tetrahydrofuran (50 mL). The water was removed and the organic phase was washed with water (3×100 mL), saturated sodium chloride (100 mL), dried over magnesium sulfate, and evaporated to give the title compound (21) as a yellow solid (18.4 g, 33%).

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