Water → (2R)-3-methyl-2-(naphthalen-2-ylsulfonylamino)butanoic acid

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Reaction Steps

To a 12-L 3-neck flask with a mechanical stirrer, an addition funnel, and a thermometer were added 400 g (3.414 mol) of D-valine (36.0), 3 L of water, 380 mL of THF, and 1190 mL (8.572 mol) of triethylamine (TEA). To this solution was added dropwise at 5°-10° C. a solution of 774 g (3.414 mol) of 2-naphthalenesulfonyi chloride (35.0) in 800 mL THF. The mixture was allowed to warm to room temperature and stirred for 2 hours. Evaporation of THF followed by quenching into 4 L of 3 N HCl precipitated crude product. Crystallization of the crude product from t-butyl methyl ether gave 910 g (87%) of 18.1. M.p: 170°-172° C. (literature gives the m.p. as 170°-172° C.-see Kiyooka, S.; Kaneko, Y.; Komura, M.; Matsuo, H.; Nakano, M. J. Org. Chem., 1991, 56, 2276.). The spectrum data are identical to that of the literature.

Provenance & Evidence