Dimethyl Sulfoxide → tert-butyl (2S,4S)-4-(benzyloxymethyl)-5-methyl-1-oxohexan-2-ylcarbamate

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Reaction Steps

A solution of DMSO (7.58 g, 97.2 mmol) in anhydrous CH2Cl2 (100 mL) was added dropwise to a stirred solution of oxalyl chloride (4.2 mL, 48.6 mmol) in anhydrous CH2Cl2 (150 mL) under N2 at −50° C. to −60° C. After 15 min, tert-butyl (2S,4S)-4-(benzyloxymethyl)-1-hydroxy-5-methylhexan-2-ylcarbamate (14.2 g, 40.5 mmol) in CH2Cl2 (100 mL) was added dropwise over 30 min, and stirred for about 60 min. Triethylamine (27 mL, 203 mmol) was added and the mixture was stirred overnight. Water was added, the organic layer was separated, and the aqueous layer was extracted with CH2Cl2. The combined organic layers were washed with 5% aq Na2CO3 and brine, dried over Na2SO4 and evaporated. The residue was purified by flash chromatography on silica gel to give tert-butyl (2S,4S)-4-(benzyloxymethyl)-5-methyl-1-oxohexan-2-ylcarbamate (14 g, 99%), which was used for next step without purification; MS: 350 (M++1).

Provenance & Evidence