Imidazole → (4R,4aS,7R,7aR)-7-ethoxy-2,2-dimethyl-4-vinyltetrahydro-6H-furo[3,2-d][1,3]dioxin-6-one

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Reaction Steps

2.12 g of imidazole (31.13 mmol) and 10.37 g of triphenylphosphine supported by a styrene copolymer (Fluka, cas: 39319-11-4, 31.13 mmol) are added to a 250 mL three-necked flask containing 2.15 g of 49 (7.78 mmol) and 100 mL of toluene, with stirring and under an argon atmosphere. The medium is heated to the reflux temperature, and 5.93 g of iodine (23.35 mmol) are added in small portions. The heating is continued for 2 h, and then the mixture is cooled, the resin is filtered and washed with 20 mL of toluene and 50 mL of AcOEt. The filtrate is washed twice with 150 mL of a solution of water saturated with NaHCO3. The organic phase is dried over anhydrous magnesium sulphate, filtered and then evaporated to dryness. The crude product is chromatographed on a silica cartridge (250 g, eluent CH2Cl2/MeOH— in a 0 to 10% MeOH gradient). 800 mg of expected product 50 are recovered.

Provenance & Evidence