Concentration dependence of the sharpless asymmetric amidohydroxylation ofisopropyl cinnamate

[GRAPHICS] A need to prepare large quantities of phenylisoserine for the semisynthesis of paclitaxel prompted us to examine the Sharpless amidohydroxylation reac tion to see if it could be run at concentrations greater than those reporte d in the literature. During these investigations, we discovered that the am ount of amidoalcohol produced in the reaction decreased while the diol side product increased as the concentration increased. We discovered that aceta mide suppresses this side reaction and allows us to run the chemistry at 0. 1 g/mL rather than the 0.014 g/mL reported in the literature.