Diisopropylethylamine → tert-butyl (2R,3R,4S)-5-azido-3-(tert-butyldimethylsilyloxy)-1-hydroxy-4-methylpentan-2-ylcarbamate

Participants

Reaction Steps

To a solution of (R)-tert-butyl 4-((1R,2S)-3-azido-1-(tert-butyldimethylsilyloxy)-2-methylpropyl)-2,2-dimethyloxazolidine-3-carboxylate (1.0 equiv.) in EtOH (0.1 M) was added PPTS (1.3 equiv.) and the mixture was refluxed for 2 days. The volatiles were removed under vacuo, the residue was dissolved in DCM (0.1 M) and DIEA (1.5 equiv.) and Boc2O (1.0 equiv.) were added to the reaction mixture. The solution was stirred for 3 hours at room temperature. The solvents were removed under reduced pressure and the residue was diluted with ethyl acetate, washed with water, aqueous NaHSO4, aqueous NaHCO3, sat. NaCl, the organic phase was dried with magnesium sulfate, filtered, and concentrated. The residue was purified via silica gel column chromatography eluting with ethyl acetate and hexanes (1:3) to give tert-butyl (2R,3R,4S)-5-azido-3-(tert-butyldimethylsilyloxy)-1-hydroxy-4-methylpentan-2-ylcarbamate as the major isomer (5:2) in 70% yield. LC/MS=289.3 (M+H-Boc), Rt=0.76 min (Frac 65%-95% method).

Provenance & Evidence