“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.
Synthesis of Isoindole Derivatives by Palladium-Catalyzed Domino Reaction of (2-Alkynyl)phenylketone O-Pentafluorobenzoyloximes
作者:Mitsuru Kitamura、Yohei Moriyasu、Tatsuo Okauchi
DOI:10.1055/s-0030-1259556
日期:2011.3
Isoindole derivatives were synthesized by the palladium-catalyzed cyclization of (2-alkynyl)phenylketone O-pentafluorobenzoyloximes in the presence of organometallic compounds such as sodium formate and aryl boronic acid.
A highly diastereo- and enantioselectivering-opening/cycloaddition reaction of cyclobutenones with 2-hydroxyacetophenones or salicylaldehyde was achieved by employing a chiral N,N′-dioxide-scandium(III) complex as the catalyst. It provided various 3-phenylvinyl-4-hydroxy-dihydrocoumarins in good yields (up to 92%), high enantioselectivities (up to 93% ee), and excellent diastereoselectivities (>19:1
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