Selectivity control in hydrogenation through adaptive catalysis using ruthenium nanoparticles on a CO2-responsive support.

With the advent of renewable carbon resources, multifunctional catalysts are becoming essential to hydrogenate selectively biomass-derived substrates and intermediates. However, the development of adaptive catalytic systems, that is, with reversibly adjustable reactivity, able to cope with the intermittence of renewable resources remains a challenge. Here, we report the preparation of a catalytic system designed to respond adaptively to feed gas composition in hydrogenation reactions. Ruthenium nanoparticles immobilized on amine-functionalized polymer-grafted silica act as active and stable catalysts for the hydrogenation of biomass-derived furfural acetone and related substrates. Hydrogenation of the carbonyl group is selectively switched on or off if pure H2 or a H2/CO2 mixture is used, respectively. The formation of alkylammonium formate species by the catalytic reaction of CO2 and H2 at the amine-functionalized support has been identified as the most likely molecular trigger for the selectivity switch. As this reaction is fully reversible, the catalyst performance responds almost in real time to the feed gas composition.

C-H and N-H bond annulation of aryl amides with unactivated olefins by merging cobalt(iii) and photoredox catalysis.

A mild, environment-friendly protocol has been developed to carry out the [4+2] annulation of aryl amides with unactivated olefins. A range of sterically and electronically diverse aryl amides and unactivated olefins were successfully employed under the developed conditions to get a variety of dihydroisoquinolinones in good-to-excellent yields.

CoIII -Catalyzed Isonitrile Insertion/Acyl Group Migration Between C-H and N-H bonds of Arylamides.

A general efficient and site-selective cobalt-catalyzed insertion of isonitrile into C-H and N-H bonds of arylamides through C-H bond activation and alcohol assisted intramolecular trans-amidation is demonstrated. This straightforward approach overcomes the limitation by the presence of strongly chelating groups. Isolation of CoIII -isonitrile complex B has been achieved for the first time to understand the reaction mechanism.

Cp*CoIII -Catalyzed Bis-isoquinolone Synthesis by C-H Annulation of Arylamide with 1,3-Diyne.

Cp*CoIII -catalyzed highly regioselective mono- and bis-annulation of arylamides with 1,3-diynes using N-OMe as an internal oxidant is demonstrated. This atom-economical transformation does not require any external oxidant and tolerates many functional groups. Various symmetrical and unsymmetrical heterocycles (homo and hetero) are accessed with predictable regio- and chemoselectivity.

C-8-Selective Allylation of Quinoline: A Case Study of ß-Hydride vs ß-Hydroxy Elimination.

An unprecedented C(8)-H bond allylation of quinoline with allyl carbonate and allyl alcohol catalyzed by Cp*Co(III) using a traceless directing group via ß-oxygen and ß-hydroxy elimination is described. This site-selective allylation reaction proceeds smoothly with various functional group tolerance including quinoxaline and phenanthridine. Under the nonoxidative reaction conditions, the difference in selectivity between Rh(III) and Co(III), which proceeds through ß-hydride and ß-hydroxy elimination using allyl alcohol, is shown for the first time.

Cobalt Catalyzed C-H and N-H Bond Annulation of Sulfonamide with Terminal and Internal Alkynes.

Chelate assisted cobalt catalyzed C-H and N-H annulation of aryl sulfonamide with terminal and internal alkynes is reported. Very high regioselectivity and excellent functional group tolerance were achieved using oxygen as a co-oxidant. The reaction is scalable under mild conditions.

Cobalt(III)-Catalyzed Dehydrative [4+2] Annulation of Oxime with Alkyne by C-H and N-OH Activation.

Efficient, scalable cobalt-catalyzed redox-neutral [4+2] annulation of readily available oximes and alkyne is reported. The developed synthetic methodology is widely applicable and tolerates various functional groups including heterocycles. A stable Cp*Co(III) neutral complex is employed as the catalyst for this redox-neutral [4+2] annulation reaction, which progresses smoothly by way of a reversible cyclometallation without any external oxidizing agent, and produces only water as the side product.

Carboxylate Assisted Ni-Catalyzed C-H Bond Allylation of Benzamides.

A one-step synthetic method was developed for allylation of benzamides using Ni(COD)2/RCO2 H and [Ni(µ-H2O)(OOCCMe3)2 (HOOCCMe3)2]2 (A') catalytic system. Efficient, well-defined, air and moisture-stable Ni-pivalate complex was isolated and employed in catalytic allylation. The influence of solvent on product selectivity was also investigated.