Dimethyl Sulfoxide → HCID 86598720, 화합물

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A solution of the product of Example 143B (2.26 g) in dichloromethane (20 mL) was treated with oxalyl chloride (5.4 mL, 1.5 equivalents) at −78° C., and stirred for 15 min. DMSO (1.02 mL, 2 equivalents) was added dropwise at −78° C., stirred for 15 min, and quenched with triethylamine (4 mL, 4 equivalents) as the mixture warmed to 0° C. The mixture was quenched with 20% KH2PO4, and partitioned between dichloromethane and water. The organic layer was washed with brine, dried over Na2SO4, filtered, and the solvents were evaporated. To this crude product was added methanol/water (7:2), (L)-valine methyl ester (1.21 g, 1 equivalent), sodium acetate trihydrate (1.96 g, 2 equivalents), and NaCNBH3 (0.95 g, 2 equivalents) was added portionwise over 30 min. After stirring for 1 hour the mixture was partitioned between saturated NaHCO3 and extracted with ethyl acetate (2×). The combined organic layer was washed with brine, dried with Na2SO4, and evaporated. The residue was treated with dichloromethane/trifluoacetic acid (10 mL, 1:1) and stirred at 25° C. for 2 hrs and concentrated.

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