Rhodium-Catalyzed Atroposelective [2 + 2 + 2] Cycloaddition of <i>Ortho</i>-Substituted Phenyl Diynes with Nitriles: Effect of <i>Ortho</i> Substituents on Regio- and Enantioselectivity
Axially chiral 3-(2-halophenyl)pyridines were successfully synthesized in high yields with excellent enantioselectivity by the cationic rhodium(I)/(S)-H8–BINAP complex-catalyzed atroposelective [2 + 2 + 2] cycloaddition of (o-halophenyl)diynes with nitriles. Interestingly, regio- and enantioselectivity highly depend on ortho substituents on the phenyl group of diynes. When the ortho substituents were
Catalyst-Free Aromatic Radiofluorination via Oxidized Iodoarene Precursors
作者:Young-Do Kwon、Jeongmin Son、Joong-Hyun Chun
DOI:10.1021/acs.orglett.8b03450
日期:2018.12.21
Oxidizediodoarenes (OIAs), prepared via mCPBA-mediated oxidation, have been demonstrated as versatile precursors for the synthesis of [18F]fluoroarenes in the absence of catalysts. OIAs have been identified as intermediates in single-pot syntheses of iodonium salts and ylides but have never been recognized as radiofluorinationprecursors. Here, the isolated OIAs were used without any catalysts to
acrylates, and substituted styrenes with 2-iodo-N,N-diisopropylferrocencarboxamide. Furthermore, the developed three-component Catellani method proceeded with the retention of the configuration of the planar chiral ferrocene, which depends on the role of the participating carbon–iodine bond in ferrocene. Consequently, the developed protocol enabled the formation of densely substituted chiral 2-aryl
Intramolecular Trapping of Allenylzincs by Carbonyl Groups
作者:Suribabu Jammi、Julien Maury、Jean-Simon Suppo、Michèle P. Bertrand、Laurence Feray
DOI:10.1021/jo4022293
日期:2013.12.20
Allenylzinc formed via oxygen-promoted zinc/iodineexchangebetween propargyl iodides and diethylzinc can be trapped by intramolecular reaction with various electrophiles such as aldehydes, ketones, esters, carbamates, and imides. Potentially useful building blocks were obtained in high yields.
Broad-Scope Rh-Catalyzed Inverse-Sonogashira Reaction Directed by Weakly Coordinating Groups
作者:Eric Tan、Ophélie Quinonero、M. Elena de Orbe、Antonio M. Echavarren
DOI:10.1021/acscatal.7b04395
日期:2018.3.2
We report the alkynylation of C(sp2)-H bonds with bromoalkynes (inverse-Sonogashira reaction) directed by synthetically usefulester, ketone, and ether groups under rhodium catalysis. Other less common directing groups such as amine, thioether, sulfoxide, sulfone, phenolester, and carbamate are also suitable directing groups. Mechanistic studies indicate that the reaction proceeds by a turnover-limiting