Enantioselective Conia-Ene-Type Cyclizations of Alkynyl Ketones through Cooperative Action of B(C<sub>6</sub>F<sub>5</sub>)<sub>3</sub>, <i>N</i>-Alkylamine and a Zn-Based Catalyst
作者:Min Cao、Ahmet Yesilcimen、Masayuki Wasa
DOI:10.1021/jacs.8b13757
日期:2019.3.13
An efficient and highly enantioselective Conia-ene-type process has been developed. Reactions are catalyzed by a combination of B(C6F5)3, an N-alkylamine and a BOX-ZnI2 complex. Specifically, through cooperative action of B(C6F5)3 and amine, ketones with poorly acidic α-C-H bonds can be converted in situ to the corresponding enolates. Subsequent enantioselective cyclization involving a BOX-ZnI2-activated
Repurposing π Electrophilic Cyclization/Dealkylation for Group Transfer
作者:Joseph A. Kaplan、Adena Issaian、Martin Stang、David Gorial、Suzanne A. Blum
DOI:10.1002/anie.202112351
日期:2021.12
Hijacking electrophiliccyclization intermediates allows for a pathway to acyclic tri- and tetrasubstituted alkenes with predictable regio- and stereochemistry. Mechanistic studies indicate concerted thioboration of the alkyne precedes rate-determining ring opening and investigate the effects of ring-size and functional groups on reaction selectivity.
Catalyst-Free Formal Thioboration to Synthesize Borylated Benzothiophenes and Dihydrothiophenes
作者:Darius J. Faizi、Ashlee J. Davis、Fiach B. Meany、Suzanne A. Blum
DOI:10.1002/anie.201608090
日期:2016.11.7
isolated prior to downstream functionalization. This methodology has been extended to the synthesis of borylated dihydrothiophenes. Mechanistic experiments suggest that the operative mechanistic pathway is through boron‐induced activation of the alkyne followed by electrophilic cyclization, as opposed to S−B σ bond formation, providing a mechanistically distinct pathway to the thioboration of C−C π bonds.
Cu-Catalyzed Tandem Aerobic Oxidative Cyclization for the Synthesis of 3,3′-Bipyrroles from the Homopropargylic Amines
作者:Zhenjie Qi、Yong Jiang、Bingxiang Yuan、Yanning Niu、Rulong Yan
DOI:10.1021/acs.orglett.8b02201
日期:2018.8.17
Cu-catalyzed method for the synthesis of 3,3′-bipyrroles from homopropargylic amines through tandem aerobic oxidative cyclization involving the formation of C–C bond has been developed. The features of this reaction are a small number of Cu catalysis and simple starting substrates. Moreover, this procedure exhibits good functional group tolerance and a series of 3,3′-bipyrroles derivatives are obtained
Divergent Gold(I)-Catalyzed Skeletal Rearrangements of 1,7-Enynes
作者:Rebecca Meiß、Kamal Kumar、Herbert Waldmann
DOI:10.1002/chem.201502843
日期:2015.9.21
The gold(I) complex catalyzed cycloisomerization and skeletal rearrangement of 1,n‐enynes (n=5–7) is a powerful methodology for the efficient synthesis of complex molecular architectures. In contrast to 1,6‐enynes, readily accessible homologous 1,7‐enynes are largely unexplored in such transformations. Here, the divergent skeletal rearrangement of all‐carbon 1,7‐enynes by catalysis with a cationic