Trifluoroacetic acid → HCID 18661316, compound

Participants

Reaction Conditions

Reaction Steps

To a stirred solution of the above (11) (0.71 mMol) in dry DMF (20 mL) at 0° C. in a dewar flask was added triethylamine (200 mL, 1.42 mMol), NaHCO3 (300 mg, 3.57 mMol), and finally diphenylphosphorylazide (250 mL, 1.2 mMol). After stirring at 0° C. for 24 h the reaction was evaporated under reduced pressure, taken up in ethyl acetate (100 mL), washed with H2O, brine, dried (MgSO4), filtered and evaporated. The remaining residue was purified by silica gel chromatography eluted with ethyl acetate in hexane. The fully protected intermediate obtained was then treated with 50% trifluoroacetic acid in CH2Cl2 (15 mL) for 45 min. at room temperature, evaporated under reduced pressure, triturated with ether, filtered and dried under vacuum to give the fully deprotected intermediate. This was treated with di-t-butyldicarbonate and triethylamine overnight at room temperature in DMF, evaporated under reduced pressure, taken up into ethyl acetate and washed with 1N NaHSO4, water and brine, dried (MgSO4), filtered and evaporated. The residue was purified by silica gel chromatography eluted with ethyl acetate in hexane to give the title product (12).

Provenance & Evidence