C(NC(C)C)(C)C.C([Li])CCC.[C:13]([O:16][C:17]([CH3:20])([CH3:19])[CH3:18])(=[O:15])[CH3:14].[CH3:21][C@H:22]([CH2:28][CH2:29][CH2:30][CH3:31])[CH2:23][C:24](OC)=[O:25].[Cl-].[NH4+]>C1COCC1.CCCCCC>[CH3:21][C@H:22]([CH2:28][CH2:29][CH2:30][CH3:31])[CH2:23][C:24](=[O:25])[CH2:14][C:13]([O:16][C:17]([CH3:20])([CH3:19])[CH3:18])=[O:15]In a 1 flask were charged 370 ml of dried THF and 38.4 g of diisopropylamine in a nitrogen stream, and the solution was cooled to -10° to -5° C. To the solution was added dropwise a 1.6 mole/l hexane solution of 238 ml of n-butyllithium at that temperature over 30 minutes, followed by stirring at that temperature for 1 hour. To the mixture was further added dropwise a solution of 44 g of t-butyl acetate in 44 ml of dried THF over 30 minutes while keeping at that temperature, followed by stirring for 1 hour. The resulting reaction mixture was cooled to -50° C., and a solution of 24 g of methyl (R)-3-methylheptanoate in 24 ml of dried THF was added thereto dropwise over 30 minutes, followed by allowing the mixture to further react at that temperature for 1.5 hours. After the reaction, a saturated ammonium chloride aqueous solution was added to the reaction mixture, and the mixture was extracted with diethyl ether. The extract was washed twice with a sodium chloride aqueous solution, and the solvent was removed by distillation under reduced pressure to obtain 45.2 g of a crude product. Purification by silica gel column chromatography gave 31.0 g (84.0%) of the titled compound.
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