Ru0·Ru n+/Al2O3 as a Versatile Catalyst in the Isomerization of Allyl Alcohol

This study focuses on examining the isomerization of allyl alcohol using ruthenium (Ru) supported on alumina as a heterogeneous catalyst. The synthesized Ru/Al solids were characterized by various characterization techniques. The content of Ru was estimated by the energy dispersive x-ray technique. The x-ray diffraction (XRD) confirmed the presence of phases in the support and active species in the catalysts. The surface area of the support after Ru impregnation and the pore volume were determined by nitrogen physisorption. The analysis of programmed temperature (TPR and TPO) shows different redox sites which is confirmed by XPS. The catalytic results suggest a dependence on the amount of available metallic Ru, as well as the importance of the continuous regeneration of the metal using H2 to achieve a good conversion of the allyl alcohol. For comparison purposes, the commercial Ru on alumina 5% (CAS 908142) was used. The results show up to 68% alcohol conversion and 27% yield of the isomerization product using Ru(1,5.4h)/Al catalyst in comparison with 86% conversion and 39% yield of the isomerization product using CAS 908142. In contrast, our catalysts always presented higher TOF values (149-160) in comparison with CAS 908142 (101).

Redox Isomerization of Allylic Alcohols Catalyzed by New Water-Soluble Rh(I)-N-Heterocyclic Carbene Complexes

New water-soluble, N-heterocyclic carbene (NHC) or mixed NHC/tertiary phosphine complexes [RhCl(cod)(sSIMes)], Na2[Rh(bmim)(cod)(mtppts)], and [Rh(bmim)(cod)(pta)]BF4 were synthetized and applied for the first time as catalysts in redox isomerization of allylic alcohols in aqueous media. [RhCl(cod)(sSIMes)] (with added sulfonated triphenylphosphine) and [Rh(bmim)(cod)(pta)]BF4 catalyzed selectively the transformation of allylic alcohols to the corresponding ketones. The highest catalytic activity, TOF = 152 h−1 (TOF = (mol reacted substrate) × (mol catalyst × time)−1) was observed in redox isomerization of hept-1-en-3-ol ([S]/[cat] = 100). The catalysts were reused in the aqueous phase at least three times, with only modest loss of the catalytic activity and selectivity.

Photoredox-Catalyzed Isomerization of Highly Substituted Allylic Alcohols by C-H Bond Activation

Photoredox-catalyzed isomerization of γ-carbonyl-substituted allylic alcohols to their corresponding carbonyl compounds was achieved for the first time by C-H bond activation. This catalytic redox-neutral process resulted in the synthesis of 1,4-dicarbonyl compounds. Notably, allylic alcohols bearing tetrasubstituted olefins can also be transformed into their corresponding carbonyl compounds. Density functional theory calculations show that the carbonyl group at the γ-position of allylic alcohols are beneficial to the formation of their corresponding allylic alcohol radicals with high vertical electron affinity, which contributes to the completion of the photoredox catalytic cycle.

Rhodium(i) diphenylphosphine complexes supported on porous organic polymers as efficient and recyclable catalysts for alkene hydrogenation

Highly stable, chemoselective and recyclable immobilized Rh(i) homogeneous catalysts for alkene hydrogenation.

Base free transfer hydrogenation using a covalent triazine framework based catalyst

Isomerisation of allylic alcohols to saturated ketones can be efficiently catalysed by a heterogeneous molecular system resulting from Ir^IIICp* anchoring to a covalent triazine framework.

Copper-loaded hypercrosslinked polymer decorated with pendant amine groups: a green and retrievable catalytic system for quick [3 + 2] Huisgen cycloaddition in water

A novel heterogeneous copper catalyst based on a 3D-network polymer containing pendant amine groups was synthesized via post-functionalization of the polymeric backbone followed by incorporation of copper(i) ions.

Pd/Al2O3-catalysed redox isomerisation of allyl alcohol: application in aldol condensation and oxidative heterocyclization reactions

The application of the Pd/Al₂O₃ catalyst in allyl alcohol isomerization and subsequent aldol-condensation and heterocyclization reactions is described.

Effect of the functionalisation route on a Zr-MOF with an Ir-NHC complex for catalysis

A new iridium N-heterocyclic carbene (NHC) metallolinker has been synthesised and introduced into a metal-organic framework (MOF), for the first time, via two different routes: direct synthesis and postsynthetic exchange (PSE). The two materials were compared in terms of the Ir loading and distribution using X-ray energy dispersive spectroscopy (EDS), the local Ir structure using X-ray absorption spectroscopy (XAS) and the catalytic activity. The materials showed good activity and recyclability as catalysts for the isomerisation of an allylic alcohol.

Ruthenium complexes with dendritic ferrocenyl phosphanes: synthesis, characterization, and application in the catalytic redox isomerization of allylic alcohols

An efficient system for the catalytic redox isomerization of the allylic alcohol 1-octen-3-ol to 3-octanone is presented. The homogeneous ruthenium(II) catalyst contains a monodentate phosphane ligand with a ferrocene moiety in the backbone and provides 3-octanone in quantitative yields. The activity is increased by nearly 90 % with respect to the corresponding triphenyl phosphane ruthenium(II) complex. By grafting the catalyst at the surface of a dendrimer, the catalytic activity is further increased. By introducing different spacers between ferrocene and phosphorus, the influence on the electronic properties of the complexes is shown by evaluating the electrochemical behavior of the compounds.

Transition metal-catalyzed redox isomerization of codeine and morphine in water

A water-soluble rhodium complex formed from commercially available [Rh(COD)(CH₃CN)₂]BF₄ and 1,3,5-triaza-7-phosphaadamantane (PTA) catalyzes the isomerization of both codeine and morphine into hydrocodone and hydromorphone in water with very high efficiency.