p-Bromobenzenesulfonyl chloride → 2-(4-Bromo-benzenesulfonylamino)-3-methyl-butyric acid methyl ester

Participants

Reaction Conditions

Reaction Steps

Step 1A [Intermediate 1] To a dry round-bottom flask was added 4-Bromo-benzenesulfonyl chloride (12.2 g, 47.7 mmol, 1 equiv.), anhydrous methylene chloride (170 mL), and H-D-Val-OMe (8.0 g, 47.7 mmol, 1 equiv.). The mixture was cooled to 0° C. in an ice bath followed by the addition of Hunig base (19.11 mL, 109.7 mmol, 2.3 equiv.). The reaction mixture was allowed to warm to room temperature and was stirred overnight. Reaction was complete as determined by TLC. The reaction mixture was then diluted with dichloromethane (100 mL) and washed with brine. The organic layer was dried over anhydrous MgSO4, solvent evaporated to yield 2-(4-Bromo-benzenesulfonylamino)-3-methyl-butyric acid methyl ester in 96% yield (16.0 g). 1H NMR (400 MHz, CHLOROFORM-D) δ ppm 0.87 (d, J=6.82 Hz, 3 H) 0.96 (d, J=6.82 Hz, 3 H) 2.04 (m, 1 H) 3.49 (s, 3 H) 3.74 (d, J=14.40 Hz, 1 H) 5.10 (d, J=9.85 Hz, 1 H) 7.66 (m, 4 H).

Provenance & Evidence