Acetic Acid → (3R*,4S*)-3-[2-(tert-Butoxy)-2-oxoethyl]-1-[(2,6-dichlorophenyl)methyl]-4-methylpyrrolidine-3-carboxylic acid

Participants

Reaction Steps

2,6-Dichlorobenzaldehyde (646 mg, 3.7 mmol) and sodium triacetoxyborohydride (782 mg, 3.7 mmol) were added to a mixture of (3R*,4S*)-3-[2-(tert-butoxy)-2-oxoethyl]-4-methylpyrrolidine-3-carboxylic acid obtained by the method of Example 2j (600 mg, 2.47 mmol), acetic acid (0.14 ml, 2.47 mmol) and methanol (10 ml), and the reaction mixture was stirred at room temperature for two hours. 2,6-Dichlorobenzaldehyde (430 mg, 2.5 mmol) and sodium triacetoxyborohydride (522 mg, 2.5 mmol) were further added, followed by stirring at an external temperature of 40° C. for 10.5 hours. Water was added to the reaction mixture, which was extracted with dichloromethane five times, and the organic layer was concentrated. The residue was purified by silica gel column chromatography (elution solvent: ethyl acetate/methanol) to give Lot A (32 mg) and Lot B (551 mg) of the title compound.

Provenance & Evidence