Dimethyl Sulfoxide → (2R,3S)-N-[(tert-Butyloxy)carbonyl]-3-amino-4-cyclohexyl-2-(triisopropylsilyloxy)butanal

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Reaction Steps

Freshly distilled dimethyl sulfoxide (0.85 g, 10.8 mmol) was added by syringe to a -78° C. solution of oxalyl chloride (0.69 g, 5.41 mmol) in anhydrous THF (22.6 mL). After 10 minutes, the alcohol of Step 3 (2 g, 4.51 mmol) in anhydrous THF (2.3 mL) was added over a period of 1.2 minutes to the -78° C. solution. The solution was stirred for 20 min. and then triethylamine (2.28 g, 22.6 mmol) was added dropwise. The 78° C. bath was removed and the reaction solution was allowed to warm to room temperature. After 1 hour at room temperature, the white, opaque mixture was poured into H2O (25 mL). The solution was extracted with ether (2×5 mL). The combined organic layers were washed with 1N HCl (25 mL), 5% NaHCO3 (25 mL) and brine (25 mL), and then dried with MgSO4. The filtrate was concentrated at 30° C. in vacuo to give the title compound as a clear, pale yellow liquid (2.08 g, 104% crude yield, TLC, 10% ethyl acetate in hexane, Rf 0.32). 1H and 13C NMR spectral data were consistent with the proposed structure.

Provenance & Evidence