Benzenesulfonic acid, 4-methyl-, compd. with pyridine (1:1) → (1S,5R,6R,7R)-6-[(3S)-3-hydroxy-5-phenyl-1-pentenyl]-7-[(4-phenylbenzoyl)oxy]-2-oxabicyclo[3.3.0]octane-3-one

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Reaction Conditions

Reaction Steps

Pyridinium p-toluenesulfonate (50 mg) was added to a stirred solution of the compound [7a] (1.00 g) in methanol (50 mL) at room temperature. The mixture was stirred at 40-50° C. for 3-4 hours (TLC monitoring) and evaporated under reduced pressure. The residue was diluted with dichloromethane (75 mL). The solution was washed with saturated aqueous solution of sodium bicarbonate (25 mL) and brine(25 mL), dried over sodium sulfate, filtered and evaporated to give 0.69 g (81.0%) of oily residue. The residue was crystallized from a mixture of ethyl acetate and isopropyl ether to give compound [5a] as white crystals with mp 126-128° C. 1H NMR (CDCl3) is in agreement with the structure.

Provenance & Evidence