N-Hydroxytryptophan in the Synthesis of Natural Products Containing Oxidized Dioxopiperazines. An Approach to the Neoechinulin and Sporidesmin Series

Article abstract of DOI:10.1021/jo00132a032

N-Hydroxytryptophan derivatives have been synthesized via two routes.In one procedure, the indole-3-pyruvate oximes 14b,c were reduced with trimethylamine-borane in the presence of ethanolic HCl to give 18 (Scheme III); aminolysis of the latter afforded 1