ResearchPad - catalysis-|-hot-paper https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Synthesis of Fulvene Vinyl Ethers by Gold Catalysis]]> https://www.researchpad.co/article/elastic_article_6668 Regioselective switch: Gold‐catalyzed cyclization of 1,5‐diynes with ketones as reagents and solvent provides diversely substituted vinyl ethers under mild conditions. The regioselectivity of such gold‐catalyzed cyclizations is usually controlled by the scaffold of the diyne. In this work, the first solvent‐controlled switching of regioselectivity from a 6‐endo‐dig‐ to 5‐endo‐dig‐cyclization in these transformations, providing fulvene derivatives is reported (see scheme).

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<![CDATA[Synthesis of Highly Fluorinated Arene Complexes of [Rh(Chelating Phosphine)]+ Cations, and their use in Synthesis and Catalysis]]> https://www.researchpad.co/article/N5bf02705-1d78-491f-a090-ccdec03740a6

Abstract

The synthesis of rhodium complexes with weakly binding highly fluorinated benzene ligands is described: 1,2,3‐F3C6H3, 1,2,3,4‐F4C6H2 and 1,2,3,4,5‐F5C6H are shown to bind with cationic [Rh(Cy2P(CH2)xPCy2)]+ fragments (x=1, 2). Their structures and reactivity with alkenes, and use in catalysis for promoting the Tishchenko reaction of a simple aldehyde, are demonstrated. Key to the synthesis of these complexes is the highly concentrated reaction conditions and use of the [Al{OC(CF3)3}4] anion.

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<![CDATA[Bis‐Cyclometalated Indazole Chiral‐at‐Rhodium Catalyst for Asymmetric Photoredox Cyanoalkylations]]> https://www.researchpad.co/article/Nc8ed3d4d-972e-43c1-ad80-85532cf6bc34

Abstract

A new class of bis‐cyclometalated rhodium(III) catalysts containing two inert cyclometalated 6‐tert‐butyl‐2‐phenyl‐2H‐indazole ligands and two labile acetonitriles is introduced. Single enantiomers (>99 % ee) were obtained through a chiral‐auxiliary‐mediated approach using a monofluorinated salicyloxazoline. The new chiral‐at‐metal complex is capable of catalyzing the visible‐light‐induced enantioselective α‐cyanoalkylation of 2‐acyl imidazoles in which it serves a dual function as the chiral Lewis acid catalyst for the asymmetric radical chemistry and at the same time as the photoredox catalyst for the visible‐light‐induced redox chemistry (up to 80 % yield, 4:1 d.r., and 95 % ee, 12 examples).

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