Methanesulfonyl chloride → (2R,3R,4S)-5-azido-2-(tert-butoxycarbonylamino)-3-(tert-butyldimethylsilyloxy)-4-methylpentyl methanesulfonate

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Reaction Steps

To a solution of tert-butyl (2R,3R,4S)-5-azido-3-(tert-butyldimethylsilyloxy)-1-hydroxy-4-methylpentan-2-ylcarbamate (1.0 equiv.) in pyridine (0.2 M) was added MsCl (1.3 equiv.) followed by DMAP (catalytic amount) at 0° C. The mixture was stirred at that temperature for 1 hour. The solution was diluted with ether and ethyl acetate (4:1), washed with aq. NaHSO4, sat. NaHCO3, brine, dried over magnesium sulfate, filtered, and concentrated. The residue was purified by silica gel column chromatography eluting with ethyl acetate and hexanes (1:3) to give (2R,3R,4S)-5-azido-2-(tert-butoxycarbonylamino)-3-(tert-butyldimethylsilyloxy)-4-methylpentyl methanesulfonate as the major isomer (5:2) in 90% yield. LC/MS=367.3 (M+H-Boc), Rt=0.81 min (Frac 65%-95% method).

Provenance & Evidence