N-[4-methoxybenzenesulfonyl]-(D)-valine → N-[(4-methoxyphenyl)sulfonyl]-D-valine tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

To an ice-cooled solution of 2(R)-(4-methoxybenzenesulfonylamino)-3-methylbutyric acid (7.0 g, 21.25 mmol) in dry methylene chloride was added N,N′-diisopropyl-O-tert-butylisourea (12.1 mL, 3.5M) via addition funnel over 45 min. The reaction mixture was maintained at 0° C. for 2 h and then allowed to warm to room temperature overnight. The reaction mixture was loaded onto a flash silica gel column and eluted with ethyl acetate/hexane (5%) to give 2(R)-(4-methoxybenzenesulfonylamino)-3-methylbutyric acid tert-butyl ester (7.02 g) as a white crystalline solid.

Provenance & Evidence