Ammonia borane-enabled hydrogen transfer processes: Insights into catalytic strategies and mechanisms

Li, Hu; Zhang, Heng; Yang, Song; Riisager, Anders

doi:10.1016/j.gee.2022.03.011

Cited by 29 publications

(25 citation statements)

References 161 publications

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“…To further reveal the influence of NH 3 ∙BH 3 on the selectivities of products, 1 H‐nuclear magnetic resonance ( 1 H‐NMR) was performed to study the interaction between NH 3 ∙BH 3 and NO 2 /CC. [ 34 ] After mixing styrene (contains CC) with NH 3 ∙BH 3 , no obvious changes were observed in the peak positions in the NMR spectra, suggesting the weak interaction between NH 3 ∙BH 3 and CC (top in Figure 4e). In contrast, peaks in 1 H‐NMR spectra moved to low chemical shift after mixing nitrobenzene (contains NO 2 ) with NH 3 ∙BH 3 , which demonstrated the strong interaction between NH 3 ∙BH 3 and NO 2 (bottom in Figure 4e).…”

Section: Resultsmentioning

confidence: 99%

Stable and Ordered Body‐Centered Cubic PdCu Phase for Highly Selective Hydrogenation

Liu

Guo

et al. 2023

Small Methods

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Phase engineering of nanomaterials plays a crucial role for regulating the catalytic performance. Nevertheless, great challenges still remain for elucidating the structure–selectivity correlation. Herein, this study demonstrates that the body‐centered cubic phase of PdCu (bcc‐PdCu) can serve as a highly active and selective catalyst for 3‐nitrostyrene (NS) hydrogenation under mild conditions. In particular, bcc‐PdCu displays a 3‐nitro‐ethylbenzene (NE) selectivity of 93.8% with a turnover frequency (TOF) value of 4573 h−1 at 30 °C in the presence of H2. With the assistance of NH3∙BH3, the selectivity of 3‐amino‐styrene (AS) reaches 94.5% with a TOF value of 13 719 h−1. Detailed experimental and theoretical calculations reveal that improved NE selectivity is ascribed to the selective adsorption of the CC bond and desorption of NE on bcc‐PdCu. Moreover, the presence of NH3∙BH3 facilitates the selective hydrogenation of NO2 due to their strong interaction and thus leads to the formation of AS. This work provides an efficient selective catalyst for NS hydrogenation under mild conditions, which may attract immediate interests in the fields of materials, chemistry, and catalysis.

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Section: Resultsmentioning

confidence: 99%

Stable and Ordered Body‐Centered Cubic PdCu Phase for Highly Selective Hydrogenation

Liu

Guo

et al. 2023

Small Methods

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“…Considering the previous results, we chose to study the more challenging alkenes and alkynes, whose hydrogenation likely proceed via a stepwise transfer when the alkenes are highly polarized (Figure 2b). [8g,16–18] To gauge the reactivity of our amine‐borane oligomers, we selected two electron‐poor yet symmetrical alkynes, the dimethyl acetylenedicarboxylate (DMAD) and the diethyl acetylenedicarboxylate (DEAD), so as not to facilitate the hydrogenation by tweaking the electronic configuration of the unsaturations. We also picked dimethyl fumarate and dimethyl maleate – the corresponding electron‐poor alkenes.…”

Section: Resultsmentioning

confidence: 99%

Catalyst‐Free Transfer Hydrogenation from Amine‐Borane Small Oligomers

Le Moigne,

Posenato,

Gajan

et al. 2023

Chemistry A European J

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Amine‐borane dimers and oligomers with varied steric and electronic profiles were prepared via capping agent‐controlled AA/BB polycondensations. They were used for transfer hydrogenations to aldehydes, ketones, imines as well as electron‐poor alkene/alkyne moieties. The amine‐borane Lewis‐paired oligomers and the congested bis(amine‐borane)s provided the highest yields. This was likely helped by facilitated dissociation (oligomers) or H‐bond assistance. In the case of the oligomers, the second equivalent of H2 present was also engaged in the reaction. Solid‐state NMR characterization provides evidence that the boron‐containing materials obtained after transfer dehydrogenation are highly similar to those obtained from thermal dehydrogenation. The oligomers bridge the gap between simple amine‐borane molecular reductants and the poly‐amine‐boranes and provide a full picture of the reactivity changes at the different scales.

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“…Ammonia borane is widely known for its advantageous properties as a potential hydrogen storage material and its reductive capacity in organic transformations. 55,56 On this matter, Yang, Du, and co-workers developed an innovative application of CPAs for the enantioselective transfer hydrogenation of imines or β-enamino esters with ammonia borane (Scheme 7). 57 The optimized reaction highlighted the need for water in the reaction media in order to regenerate the chiral ammonia borane.…”

Section: Reviewmentioning

confidence: 99%