“One-Pot” Access to 4<i>H</i>-Chromenes with Formation of a Chiral Quaternary Stereogenic Center by a Highly Enantioselective Iminium-allenamine Involved Oxa-Michael−Aldol Cascade
作者:Chunliang Liu、Xinshuai Zhang、Rui Wang、Wei Wang
DOI:10.1021/ol102096s
日期:2010.11.5
organocatalytic highlyenantioselectivecascade Michael−aldol reaction has been developed in high yields under mild reaction conditions. The “one-pot” process affords an efficient approach to the synthetically and biologically important chiral4H-chromenes bearing a quaternary stereogenic center. The study significantly expands the scope of less explored organocatalytic iminium-allenamine chemistry.
developed, providing various chiral α-monosubstituted α-aminoacidderivatives with excellent results (97-99% yields, 90 to >99% ee). Cyclic N-sulfonyl ketimines were also hydrogenated well to afford chiral amine derivatives with 98-99% yields and 97 to >99% ee. The gram-scale asymmetric hydrogenation was performed well with 85% yield and 99% ee using only 0.2 mol% catalyst.
Phosphine-Catalyzed (4 + 1) Annulation of <i>o</i>-Hydroxyphenyl and <i>o</i>-Aminophenyl Ketones with Allylic Carbonates: Syntheses and Transformations of 3-Hydroxy-2,3-Disubstituted Dihydrobenzofurans and Indolines
作者:Zifeng Qin、Wei Liu、Danyang Wang、Zhengjie He
DOI:10.1021/acs.joc.6b00596
日期:2016.6.3
A phosphine-catalyzed (4 + 1) annulationreaction of o-hydroxyphenyl and o-aminophenyl ketones with ester-modified allylic carbonates has been developed, providing a facile and efficient method to synthesize functionalized 2,3-disubstituted dihydrobenzofurans and indolines. Under mild conditions and in the catalysis of PPh3 (20 mol %), the reactions of o-hydroxyphenyl or o-aminophenyl ketones readily
P(NMe<sub>2</sub>)<sub>3</sub>-Mediated Reductive Intramolecular Annulation of Benzoylformates Tethered with a Trisubstituted Alkene Unit and Synthesis of 2,2-Disubstituted 2<i>H</i>-Chromenes
作者:Jiayong Zhang、Yuhe Qiu、Biao Zhang、Zhiqiang Huang、Zhengjie He
DOI:10.1021/acs.orglett.1c00286
日期:2021.3.5
report, a P(NMe2)3-mediated reductive intramolecular annulation reaction has been developed with benzoyl formates bearing a trisubstituted alkene unit. It provides a facile synthesis of highly functionalized 2,2-disubstituted 2H-chromenes with a broad substratescope and high efficiency. Experimental results suggest this annulation reaction proceeds via a cascade of alkene isomerization/vinyl o-quinone
Lewis Base-Catalyzed Intramolecular Vinylogous Aldol Reaction and Chemoselective Syntheses of 3-Hydroxy-2,3-Disubstituted Dihydrobenzofurans and Indolines
作者:Jiayong Zhang、Zhengjie He
DOI:10.1021/acs.joc.3c01313
日期:2023.9.15
A Lewis base-catalyzed intramolecular vinylogous aldol reaction of o-(allyloxy)phenyl ketoesters or o-(allylamino)phenyl ketoesters has been developed. This reaction provides ready access to 3-hydroxy-2,3-disubstituted dihydrobenzofurans and indolines in high yields with excellent chemoselectivity and diastereoselectivity. An acid-promoted dehydration of such products further extends the utility of