4-Nitrobenzenesulfonyl chloride → 3-(4-Benzyloxy-phenyl)-2-[4-methyl-2-(4-nitro-benzenesulfonylamino)-pentanoylamino]-propionic acid tert-butyl ester

Participants

Reaction Steps

A solution of the product from Example AI ([S-(R*,R*)]-2-(2-amino-4-methyl-pentanoylamino)-3-(4-benzyloxy-phenyl)-propionic acid tert-butyl ester) (308 mg, 0.70 mmol), 4-nitrobenzenesulfonyl chloride (190 mg, 0.77 mmol), N,N-diisopropylethyl-amine (181 mg, 1.4 mmol) and DMAP (20 mg), in benzene (5 mL) was heated under reflux for 3 hours, then concentrated in vacuo and the residue dissolved in ethyl acetate, and washed with saturated NaHCO3 solution, water, and brine, dried over anhydrous sodium sulfate, and concentrated in vacuo. The tan solid thus obtained was triurated in warm tert-butylmethyl ether, and filtered to give 419 mg (95%) of the title compound as a white solid, mp=121-123° C.

Provenance & Evidence