Catalytic Asymmetric Heterodimerization of Ketenes
摘要:
In this Communication we describe an unprecedented catalytic asymmetric heterodimerization of ketenes of wide substrate scope. The alkaloid-catalyzed method provides access to ketene heterodimer beta-lactones and allows even two different monosubstituted ketenes to be cross-dimerized, with excellent enantioselectivity (17 examples with >= 90% ee) and excellent heterodimer regioselectivity observed in all cases.
A flexible and functional group tolerant synthesis route to access a structurally diverse collection of bifunctional 6′-(thio)-urea containing Cinchona alkaloid-based chiral quaternary ammonium salts has been developed. This route gives access to more than 25 different novel urea- and thiourea-containing ammonium salt derivatives, which were not accessible so far.
C−H Cyanation of 6-Ring N-Containing Heteroaromatics
作者:Bryony L. Elbert、Alistair J. M. Farley、Timothy W. Gorman、Tarn C. Johnson、Christophe Genicot、Bénédicte Lallemand、Patrick Pasau、Jakub Flasz、José L. Castro、Malcolm MacCoss、Robert S. Paton、Christopher J. Schofield、Martin D. Smith、Michael C. Willis、Darren J. Dixon
DOI:10.1002/chem.201703931
日期:2017.10.20
them have the potential for far‐reaching impact across synthetic chemistry and the biomedical sciences. Herein, we report an approach to heteroaromatic C−H cyanation through triflic anhydrideactivation, nucleophilicaddition of cyanide, followed by elimination of trifluoromethanesulfinate to regenerate the cyanated heteroaromatic ring. This one‐pot protocol is simple to perform, is applicable to a broad
Cation-Controlled Enantioselective and Diastereoselective Synthesis of Indolines: An Autoinductive Phase-Transfer Initiated 5-<i>endo</i>-<i>trig</i> Process
作者:Krishna Sharma、Jamie R. Wolstenhulme、Phillip P. Painter、David Yeo、Francisca Grande-Carmona、Craig P. Johnston、Dean J. Tantillo、Martin D. Smith
DOI:10.1021/jacs.5b08834
日期:2015.10.21
A catalytic enantioselective approach to the synthesis of indolines bearing two asymmetriccenters, one of which is all-carbon and quaternary, is described. This reaction proceeds with high levels of diastereoselectivity (>20:1) and high levels of enantioselectivity (up to 99.5:0.5 er) in the presence of CsOH·H2O and a quinine-derived ammonium salt. The reaction most likely proceeds via a delocalized
We developed a chromium-catalyzed, photochemical, and linear-selective alkylation of aldehydes with alkylzirconium species generated in situ from a wide range of alkenes and Schwartz’s reagent. Photochemical homolysis of the C–Zr bond afforded alkyl radicals, which were then trapped by a chromium complex catalyst to generate the alkylchromium(III) species for polar addition to aldehydes. The reaction
A mild, versatile and efficient method for the regioselective hydrodifluoromethylation of unactivated alkenes has been developed. This Ag-mediated Csp(3)-CF2 bond forming reaction provides easy access to a variety of vicinal alpha-difluoroacetate-containing alkanes.