(+)-8-Phenylmenthol → (1R,2S,5R)-5-methyl-2-(1-methyl-1-phenylethyl)cyclohexyl 5-(3-bromo-4-fluorophenyl)-4,6-dioxo-1,3,4,5,6,7,8,9-octahydro-2H-cyclopenta[b][1,7]naphthyridine-2-carboxylate

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A solution of the product from Example 5A (1.9 g, 4.0 mmol) in THF (30 mL) was treated with 8-phenylmenthol chloroformate prepared from (−)-8-phenylmenthol as described in (Yamamoto, Y., J.Amer.Chem.Soc. (1992), 114, 121-125) (1.45 g, 4.92 mmol) in THF (10 mL), stirred for 3 days at ambient temperature and partitioned between aqueous sodium bicarbonate and methylene chloride. The organic layer was separated, dried with sodium sulfate, filtered and concentrated to provide a mixture of diastereomeric carbamates. The diastereomeric mixture was subjected to column chromatography over silica gel (20% hexanes/ethyl acetate) to provide the title compound (0.32 g) as the less polar diastereomer and mixed fractions containing both diastereomers (0.9 g).

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