C([Li])CCC.C(NC(C)C)(C)C.C([N-]C(C)C)(C)C.[Li+].[OH:21][C@@H:22]1[CH2:27][O:26][C:24](=[O:25])[CH2:23]1.[C:28]([O:31][C:32]([CH3:35])([CH3:34])[CH3:33])(=[O:30])[CH3:29].Cl>CCCCCC.O1CCCC1.C(OCC)(=O)C>[C:32]([O:31][C:28](=[O:30])[CH2:29][C:24](=[O:25])[CH2:23][C@H:22]([OH:21])[CH2:27][OH:26])([CH3:35])([CH3:34])[CH3:33]To 30 mL (45 mmol) of a solution of n-butyllithium in hexane (1.5 mol/L) was added a solution of diisopropylamine (5.01 g, 49.5 mmol)-tetrahydrofuran (5 mL) dropwise under stirring at 5° C., and the mixture was stirred under argon for 1 hour to prepare a lithium diisopropylamide solution. In a separate vessel, 1.02 g (10 mmol) of (S)-β-hydroxy-γ-butyrolactone and 2.32 g (20 mmol) of tert-butyl acetate were dissolved in 8.0 mL of tetrahydrofuran and the mixture was stirred under argon at 0 to 5° C. To this solution, the lithium diisopropylamide solution prepared above was added dropwise over 30 minutes, and the mixture was further stirred at 5 to 20° C. for 16 hours. In a separate vessel, 35 mL of 3N-hydrochloric acid and 30 ml of ethyl acetate were stirred to mix and the above reaction mixture was poured therein. After standing, the organic layer was taken, washed with saturated aqueous sodium chloride solution, and dehydrated over anhydrous magnesium sulfate. The solvent was then distilled off under reduced pressure and the residue was purified by silica gel column chromatography (Kieselgel 60, product of Merck; hexane:ethyl acetate=2:1) to give 124 mg of (5S)-5,6-dihydroxy-3-oxohexanoic tert-butyl ester (yellow oil). Yield 6%.
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