To a mixture of N-[rel-(4aR,6R,8aS)-8a-(5-bromo-2-fluorophenyl)-6-(1-methyl-1H-pyrazol-4-yl)-4,4a,5,6,8,8a-hexahydropyrano[3,4-d][1,3]thiazin-2-yl]benzamide [(+/−)—C46, which may be prepared in the same manner as C46, by using the chemistry described in Preparation 1 followed by Examples 10 and 12, but employing racemic 2-[(benzyloxy)methyl]oxirane as starting material] (1.0 g, 1.9 mmol) and triethylamine (580 mg, 5.73 mmol) in methanol (20 mL) and 1-methylpyrrolidin-2-one (10 mL) was added [1,1′-bis(diphenylphosphino)ferrocene]dichloropalladium(II) (140 mg, 0.19 mmol) in one portion at room temperature. The reaction mixture was stirred under carbon monoxide (2.5 MPa) at 120° C. for 18 hours, whereupon it was concentrated in vacuo to remove methanol, and partitioned between water (500 mL) and ethyl acetate (500 mL). The organic layer was washed with saturated aqueous sodium chloride solution (2×400 mL), dried over sodium sulfate, filtered, and concentrated under reduced pressure. Silica gel chromatography (Eluent: ethyl acetate) afforded the product as a red solid. Yield: 570 mg, 1.12 mmol, 59%. LCMS m/z 509.1 [M+H+].
