6-fluoro-4-oxo-4H-chromene-2-carboxylic acid → 6-fluoro-4-oxo-3,4-dihydro-2H-1-benzopyran-2-carboxylic acid

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Reaction Steps

(+)-2,3-O-isopropyliden-2,3-dihydroxy-1,4-bis(diphenylphosphyno)butane (120 mg, 0.0240 mmol) was added to a solution of dichloro-bis-[(1,3)-cyclooctadiene]-dirhodium(I) (59.2 mg, 0.0120 mmol) in dry benzene (0.5 ml) under argon atomosphere and the mixture was stirred for 15 minutes to prepare an optical active rhodium catalyst. The benzene solution (catalyst) was added to a suspension of 6-fluoro-4-oxo-4H-1-benzopyran-2-carboxylic acid (1.00 g, 4.80 mmol, obtained in Example 5) in methanol (30 ml) under argon atmosphere. Gaseous phase was changed for H2, and the mixture was stirred for 24 hours under H2 (4 kg/cm2) at 40° C.

Provenance & Evidence