Catalyst-free transfer hydrogenation of activated alkenes exploiting isopropanol as the sole and traceless reductant

Abstract

Both metal-catalyzed and organocatalytic transfer hydrogenation reactions are widely employed for the reduction of C=O and C=N bonds. However, selective transfer hydrogenation reactions of C=C bonds remain challenging. Therefore, the...

Recent progress of heterogeneous catalysts for transfer hydrogenation under the background of carbon neutrality

“…In recent years, some progress has been made in catalytic transfer hydrogenation. 21,23,24,[28][29][30][31][32][33] For example, Gilkey and Xu have reviewed the recent progress in catalytic transfer hydrogenation for the conversion of biomass-derived feedstocks to fuels and chemicals with a focus on mechanistic interpretation, and they also discussed future challenges and opportunities. 34 Currently, the common hydrogen donors mainly include low molecular mass alcohols (e.g., methanol, ethanol, and isopropanol), and formic acid is also an ideal hydrogen storage medium with a high hydrogen content of 4.4 wt% and stable chemical properties.…”

“…In recent years, some progress has been made in catalytic transfer hydrogenation. 21,23,24,28–33 For example, Gilkey and Xu have reviewed the recent progress in catalytic transfer hydrogenation for the conversion of biomass-derived feedstocks to fuels and chemicals with a focus on mechanistic interpretation, and they also discussed future challenges and opportunities. 34…”

Nanoarchitectonics of Non-Noble-Metal-Based Heterogeneous Catalysts for Transfer Hydrogenation Reactions: Detailed Insights on Different Hydrogen Sources

“…Generally, “homogeneous” and “heterogeneous” are the two types of catalysts that are investigated for the target processes. The steric and electronic properties of the homogeneous metal–ligand complexes are responsible for their great selectivity but suffer from problematic separation and reusability concerns, as well as product contamination. ,, In contrast to this, the heterogeneous catalysts are more promising for real-world applications due to easy catalyst recovery and separation. The utilization of noble-metal-based heterogeneous catalyst involving Au, Pd, Pt, Ag, Ir, Ru, Rh, etc., as active centers restricts their extensive use in large-scale industrial applications, due to the high cost of the process and limited availability of resources. − Hence, the use of noble-metal catalysts is not desirable, from an economical and sustainable point of view.…”

“…To overcome these problems and because of the drive toward a green and sustainable future, CTH from suitable hydrogen sources such as formic acid, alcohols, hydrazine hydrate, water, etc., have attracted a tremendous amount of attention for hydrogenation reactions. The main advantages of this methodology involves the following: a high-pressure reactor is not needed, simple stirring is required, there is a reduction in complexity and cost of experiment, it is easy to handle, possible casualties are minimized, and there is more selectivity in reduction reactions. ,− In the CTH process, there are three possibilities of hydrogen transfer, which were classified by Braude and Linstead as (i) transfer of hydrogen taking place within one molecule; (ii) hydrogen disproportionation occurs, which leads to the transfer of hydrogen between identical donor and acceptor molecules; and (iii) transfer hydrogenation–dehydrogenation occurs between unlike donor and acceptor molecules. , Currently, the hydrogen donors, such as alcohols, formic acid, and hydrazine hydrate are majorly utilized for the transfer hydrogenation reactions. The study of CTH methodology for organic reactions has experienced substantial growth over the decade spanning from 2014 to 2024, as shown in Figure .…”

From byproducts to NLO-active dyes: catalyst-free transfer hydrogenation in the modular synthesis of merocyanines

“…5 Furthermore, beyond a better synthetic capability in constructing molecular complexity is the lack of examples using THenabled reactions in the synthesis of amine-containing functional molecules and molecular materials. Most tertiary amine products were obtained through addition reactions to the sp 2 carbon of iminium or enamine intermediates, keeping the sp 3 hybridization for the carbon centers unchanged after the transformation (Fig. 1B).…”