Diisopropylethylamine → tert-butyl (2S,3S,E)-1-(tert-butyldimethylsilyloxy)-3-(4-(trifluoromethyl)phenyl)hex-4-en-2-ylcarbamate

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Reaction Conditions

Reaction Steps

tert-Butyl (2S,3S,E)-1-hydroxy-3-(4-(trifluoromethyl)phenyl)hex-4-en-2-ylcarbamate (1.94 g, 5.4 mmol) (prepared as shown in Scheme 19) was taken up in 50 mL of DCM and chilled to 0° C. DIEA (2.4 mL, 13 mmol) was added, followed by slow addition of tert-butyldimethylsilyl trifluoromethanesulfonate (TBSOTf) (1.5 mL, 6.5 mmol). After 45 minutes, an additional 0.20 mL of TBSOTf was added. After an additional 20 minutes, the reaction was quenched with 50 mL of aq NaHCO3. The mixture was partitioned, and the aqueous portion was extracted twice with 50 mL of DCM. The combined organic extracts were dried over MgSO4. Filtration and concentration under reduced pressure, followed by flash chromatography on silica gel (1% to 7.5% EtOAc/hexanes), afforded tert-butyl (2S,3S,E)-1-(tert-butyldimethylsilyloxy)-3-(4-(trifluoromethyl)phenyl)hex-4-en-2-ylcarbamate (2.0 g, 78% yield) as a clear oil. The oil crystallized over 12 hours. 1H NMR (400 MHz, CDCl3) δ ppm 7.54 (d, J=8.02 Hz, 2 H) 7.35 (d, J=8.02 Hz, 2 H) 5.61 (s, 1 H) 5.59 (d, J=5.87 Hz, 1 H) 4.62-4.60 (m, 1H) 3.97-3.92 (m, 1H) 3.79-3.76 (m, 1H) 3.66-3.59 (m, 2H) 1.69 (d, J=5.28 Hz, 3 H) 1.26 (s, 9 H) 0.92-0.97 (m, 9 H) 0.06 (s, 6 H).

Provenance & Evidence