V. Krasnov, G. Levit, I. M. Bukrina
Sep 9, 2002
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Journal
Tetrahedron-asymmetry
Abstract
A large laboratory scale (ca. 40 g) method for the preparation of enantiomerically pure (S)- and (R)-valine tert-butyl esters has been developed. The method involves three steps: preparation of N-TFA-valines, preparation of valine tert-butyl esters using 2-methylpropene in dioxane in the presence of sulfuric acid, and isolation of the target compounds as the acetate derivative. The overall yield is up to 70% relative to the starting valine, ee being more than 98% (by HPLC).