Vinyl chloroformate → (3aRS,7aRS)-7,7-bis(3-fluorophenyl)-2-vinyloxycarbonylperhydro-4-isoindolone

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Reaction Steps

A solution of (3aRS,7aRS)-2-benzyl-7,7-bis(3-fluorophenyl)perhydro-4-isoindolone (92.2 g) in 1,2-dichloroethane (860 cc) is treated with vinyl chloroformate (26.3 cc) and heated to reflux for 3 hours, then concentrated under reduced pressure (2.7 kPa). The residue is chromatographed (in two runs) on silica gel (particle size 0.04-0.063 mm, columns 8 cm in diameter and 35 cm high), eluting under a nitrogen pressure of 0.5 bar with a mixture of cyclohexane and ethyl acetate (75:25). The meringue-like product obtained is crystallized in isopropyl ether to give (3aRS,7aRS)-7,7-bis(3-fluorophenyl)-2-vinyloxycarbonylperhydro-4-isoindolone (50.3 g). M.p. 152° C.

Provenance & Evidence