Hydrochloric Acid → methyl (2S)-2-isocyanato-3,3-dimethylbutanoate

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Reaction Steps

A solution of methyl 3-methyl-L-valinate hydrochloride (10.0 g, 54.9 mmol) and pyridine (22.3 mL, 276 mmol) in methylenechloride (300 mL) was cooled in an ice bath under nitrogen. Phosgene (20% in toluene, 41.1 mL, 83.0 mmol) was added dropwise over 0.5 h using an addition funnel. The resulting mixture was stirred 1 h then poured into cold 1M hydrochloric acid and extracted with methylenechloride (3×100 mL). The combined organic extracts were washed with brine, dried with anhydrous magnesium sulfate, filtered and concentrated. Flash column chromatography eluting with hexane/ethyl acetate 90/10 gave methyl 3-methyl-N-(oxomethylene)-L-valinate as an orange oil, 6.99 g (74% yield).

Provenance & Evidence