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Total Synthesis of K777: Successful Application of Transition-Metal-Catalyzed Alkyne Hydrothiolation toward the Modular Synthesis of a Potent Cysteine Protease Inhibitor

TitleTotal Synthesis of K777: Successful Application of Transition-Metal-Catalyzed Alkyne Hydrothiolation toward the Modular Synthesis of a Potent Cysteine Protease Inhibitor
Publication TypeJournal Article
Year of Publication2016
AuthorsKiemele, ER, Wathier, M, Bichler, P, Love, JA
JournalOrganic Letters
Volume18
Pagination492-495
Abstract

We report the total synthesis of K777 and a series of analogues via alkyne hydrothiolation catalyzed by Wilkinson’s complex (ClRh(PPh3)3). The alkyne hydrothiolation reactions proceeded with excellent regio- and diastereoselectivity to generate the desired E-linear vinyl sulfides in high yield. The use of Ellman’s auxiliary generates the requisite propargyl amines in excellent enantiomeric excess (ee) and obviates the use of l-homophenylalanine, an expensive unnatural amino acid. The vinyl sulfone derivatives exhibit a large difference in rate toward Michael addition. Kinetic data are consistent with rate-limiting nucleophilic attack to generate the carbanion intermediate.

URLhttp://dx.doi.org/10.1021/acs.orglett.5b03535
DOI10.1021/acs.orglett.5b03535