2,6-Lutidine → (3S,5S,6R,8S)-8-Allyl-3-(tert-butyl)-6-(3-chlorophenyl)-5-(4-chlorophenyl)-8-methyl-2,3,5,6,7,8-hexahydrooxazolo[3,2-a]pyridin-4-ium triflate

Participants

Reaction Conditions

Reaction Steps

To a solution of (S)-2-((2R,3R)-2-(3-chlorophenyl)-3-(4-chlorophenyl)-3-hydroxypropyl)-N-((S)-1-hydroxy-3,3-dimethylbutan-2-yl)-2-methylpent-4-enamide (Example 363, step A, 950 mg, 1.929 mmol) in DCM (19 mL) at −50° C. was added 2,6-lutidine (896 μl, 7.72 mmol) followed by trifluoromethanesulfonic anhydride solution (1M DCM, 4.34 mL, 4.34 mmol). The progress of the reaction was monitored by LC/MS. An additional charge of 450 uL (2 eq) 2,6-lutidine followed by 1.12 eq triflic anhydride (2.16 mmol, 2.16 mL of 1M solution in dichloromethane). The reaction was allowed to warm to 0° C. and then poured into sat. aq. CuSO4 solution. To the mixture was added 100 mL ethyl acetate. The layers were separated and the organic phase was washed with sat. aq. CuSO4. The combined organic layers were concentrated and purified by column chromatography on silica gel (eluent: 20 to 50% acetone in hexanes) to afford the title compound.

Provenance & Evidence