Dimethyl Sulfoxide → 3-(RS)-formyl-4-(SR)-phenylpyrrolidine-1-carboxylic acid tert-butyl ester

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Reaction Steps

To a solution of 13.1 mL (26.25 mmol) of oxalyl chloride (2M in DCM) in 13 mL of anhydrous DCM were added 3.72 mL (52.5 mmol) of DMSO at −78° C. After 5 minutes of stirring, 3 g (10.5 mmol) of 3-(RS)-hydroxymethyl-4-(SR)-phenylpyrrolidine-1-carboxylic acid tert-butyl ester, previously dissolved in 15 mL of anhydrous DCM, were added dropwise. After 30 minutes additional agitation at −78° C., 18.5 mL (105 mmol) of DIPEA were added dropwise. An additional 30 minutes of agitation at 0° C. and the reaction mixture was quenched with 10 mL of water. 100 mL of water were again added and the solution was extracted with DCM (2×100 mL). The combined organic layers were dried over sodium sulfate, filtered and evaporated in vacuo. The crude yellow oil was purified by flash chromatography on silica gel (ethyl acetate/hexanes 0:100 to 20:80) yielding 2.42 g (83.7%) of 3-(RS)-formyl-4-(SR)-phenylpyrrolidine-1-carboxylic acid tert-butyl ester as a pale yellow oil.

Provenance & Evidence