Chiral Thioureas Promote Enantioselective Pictet–Spengler Cyclization by Stabilizing Every Intermediate and Transition State in the Carboxylic Acid-Catalyzed Reaction
作者:Rebekka S. Klausen、C. Rose Kennedy、Alan M. Hyde、Eric N. Jacobsen
DOI:10.1021/jacs.7b06811
日期:2017.9.6
mechanism of benzoic acid/thiourea co-catalysis in the asymmetric Pictet–Spengler reaction is reported. Kinetic, computational, and structure–activity relationship studies provide evidence that rearomatization via deprotonation of the pentahydro-β-carbolinium ion intermediate by a chiralthiourea·carboxylate complex is both rate- and enantioselectivity-determining. The thiourea catalyst induces rate acceleration
the enantioselective reaction of tryptamines with aldehydes (protio‐Pictet‐Spengler reactions) to give the corresponding tetrahydro‐β‐carbolines with good enantioselectivity (up to 95 % ee) by chiral anion‐binding catalysis.
The development of one-pot imine formation and asymmetric Pictet−Spenglerreactions cocatalyzed by a chiral thiourea and benzoic acid is described. Opticallyactivetetrahydro-β-carbolines, ubiquitous structural motifs in biologically active natural products, are obtained in high ee directly from tryptamine and aldehyde precursors.
描述了手性硫脲和苯甲酸共催化的一锅亚胺形成和不对称 Pictet-Spengler 反应的发展。光学活性四氢-β-咔啉是生物活性天然产物中普遍存在的结构基序,直接从色胺和醛前体以高 ee 获得。