Potassium bis(trimethylsilyl)amide → (2R,3R)-1-benzyl 4-tert-butyl 3-(3-methylisoxazol-4-yl)-2-(3,3,3-trifluoropropyl)succinate

Participants

Reaction Conditions

Reaction Steps

In a 250 mL round-bottomed flask a solution of tert-butyl 2-(3-methylisoxazol-4-yl)acetate (1.75 g, 8.87 mmol) in THF (56 mL) and toluene (27 mL) was cooled in −78° C. bath and treated with a solution of 1M KHMDS (11.09 mL, 11.09 mmol) in THF dropwise over 2 minutes via syringe. After stirring for 15 minutes at −78° C., the reaction mixture was placed in a room temperature water bath for 15 minutes and then again in −78° C. bath for another 15 minutes before a solution of Preparation 4D (R)-benzyl 5,5,5-trifluoro-2-(trifluoromethylsulfonyloxy)pentanoate (4.55 g, 11.53 mmol) in 6 mL THF and 3 mL toluene was added to the reaction over 2 minutes. The reaction mixture was stirred in −78° C. bath for 2 hours before being quenched with saturated aqueous NH4Cl and then warmed to room temperature. The mixture was diluted with brine and extracted with EtOAc. The organic layer was dried over MgSO4 filtered and concentrated. The residue was purified on silica gel column (330 g ISCO) eluting with a gradient of 0-30% EtOAc/CH2Cl2, and collected tubes containing product were concentrated to give (2R,3R)-1-benzyl 4-tert-butyl 3-(3-methylisoxazol-4-yl)-2-(3,3,3-trifluoropropyl)succinate (2.394 g, 61% yield) containing about 30% of the (2R,3S) isomer.

Provenance & Evidence