Sustainable synthesis of N-heterocycles in water using alcohols following the double dehydrogenation strategy

Maji, Milan; Chakrabarti, Kaushik; Panja, Dibyajyoti; Kundu, Sabuj

doi:10.1016/j.jcat.2019.03.028

Cited by 79 publications

(71 citation statements)

References 73 publications

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“…Catalysts able to complete the cycle of hydrogen capture and release are becoming increasingly attractive, while most reported examples are molecular catalysts based on transition metals (8)(9)(10)(11)(12)(13)(14)40). Therefore, after achieving the excellent performance of the NC-800 in acceptorless dehydrogenation of N-heterocycles, we proceeded to examine NC-800 for transfer hydrogenation of aromatic N-heterocycles (quinolines and indoles).…”

Section: Catalytic Studiesmentioning

confidence: 99%

“…Effective dehydrogenation methods have been developed based on transition metal-based catalysts (Fig. 1) (8)(9)(10)(11)(12)(13)(14). However, these catalysts often rely on critical platinum group metals (15) with limited natural abundance and commonly suffer from the drawbacks like coking, restricting continuous large-scale application.…”

Section: Introductionmentioning

confidence: 99%

“…The introduction of nitrogen can also yield carbocatalysts with active catalytic sites for the aerobic dehydrogenation (27)(28)(29), while the structures of active sites are still unclear. However, to our best knowledge, most of previous metalfree dehydrogenation of N-heterocycles required either high temperature, or excess base for hydrogen activation, or oxidants as hydrogen acceptor (14,24,30). Therefore, the development of an effective, robust metal-free catalyst operating at environmentally benign conditions is highly valuable but challenging.…”

Section: Introductionmentioning

confidence: 99%

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Metal-free carbocatalyst for room temperature acceptorless dehydrogenation of N-heterocycles

Nie

Tao

et al. 2022

Sci. Adv.

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Catalytic dehydrogenation enables reversible hydrogen storage in liquid organics as a critical technology to achieve carbon neutrality. However, oxidant or base-free catalytic dehydrogenation at mild temperatures remains a challenge. Here, we demonstrate a metal-free carbocatalyst, nitrogen-assembly carbons (NCs), for acceptorless dehydrogenation of N-heterocycles even at ambient temperature, showing greater activity than transition metal–based catalysts. Mechanistic studies indicate that the observed catalytic activity of NCs is because of the unique closely placed graphitic nitrogens (CGNs), formed by the assembly of precursors during the carbonization process. The CGN site catalyzes the activation of C─H bonds in N-heterocycles to form labile C─H bonds on catalyst surface. The subsequent facile recombination of this surface hydrogen to desorb H 2 allows the NCs to work without any H-acceptor. With reverse transfer hydrogenation of various N-heterocycles demonstrated in this work, these NC catalysts, without precious metals, exhibit great potential for completing the cycle of hydrogen storage.

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Section: Catalytic Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Metal-free carbocatalyst for room temperature acceptorless dehydrogenation of N-heterocycles

Nie

Tao

et al. 2022

Sci. Adv.

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“…The same group developed another strategy for synthesis various N‐heterocycles such as quinolines, acridines and 1,8‐naphthyridines in water (Scheme 13). [34] Author screened several Ir‐complexes and among them, complex 7 a containing both benzimidazole fragment and 2‐hydroxy pyridine moiety demonstrated superior catalytic activity. Applying this technique, synthesis of a variety of quinoline, acridine and 1,8‐naphthyridine derivatives were executed successfully by coupling different 2‐aminoaryl alcohols/2‐nitrobenzyl alcohols with various substituted secondary alcohols in water.…”

Section: Bidentate Ligandsmentioning

confidence: 99%

“…The same group developed another strategy for synthesis various N-heterocycles such as quinolines, acridines and 1,8naphthyridines in water (Scheme 13). [34] Author screened several Ir-complexes and among them, complex 7 a containing both benzimidazole fragment and 2-hydroxy pyridine moiety dem-Scheme 10. Ir-catalyzed N-methylation of amines and sulphonamides using methanol.…”

Section: D-metal Based Complexesmentioning

confidence: 99%

Alkyl Phosphine Free, Metal‐Ligand Cooperative Complex Catalyzed Alcohol Dehydrogenative Coupling Reactions

et al. 2021

Self Cite

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In last two decades alcohol has drawn a special attention as a building blocks due to its abundance, low cost and less toxic nature which can be derived from various sustainable resources. By dehydrogenation of alcohol, aldehyde/ketone can be easily accessed which can be further coupled with several nucleophiles for the construction of complex molecules. Among the various strategies, metalligand cooperation is a powerful and efficient tool for the utilization of alcohol to synthesize variety of value-added products. Numerous alkyl phosphine based bifunctional complexes are well-known in the literature for the alcohol dehydrogenative coupling reactions. However, the presence of alkyl phosphine moiety and air and moisture sensitive nature of the metal complexes hinder their broad application in catalysis. In this minireview, we highlighted air and moisture stable, metal-ligand cooperative 5d, 4d and 3d metal-based complexes which were effectively utilized to fabricate different value-added compounds by alcohol dehydrogenative coupling reactions.

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Iron Catalyzed Synthesis of Pyrimidines Under Air

et al. 2019

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Herein we report an iron-catalyzed multicomponent dehydrogenative functionalization of alcohols to pyrimidines under atmospheric conditions. Using a well-defined Fe(II)-complex featuring redox noninnocent 2-phenylazo-(1,10-phenanthroline) ligand, as a catalyst, a wide array of 2,4,6-trisubstituted pyrimidines were prepared via dehydrogenative coupling of primary and secondary alcohols with amidines under air at 100°C. A few control experiments were carried out to understand and unveil the plausible reaction mechanism.

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Sustainable synthesis of N-heterocycles in water using alcohols following the double dehydrogenation strategy

Cited by 79 publications

References 73 publications

Metal-free carbocatalyst for room temperature acceptorless dehydrogenation of N-heterocycles

Metal-free carbocatalyst for room temperature acceptorless dehydrogenation of N-heterocycles

Alkyl Phosphine Free, Metal‐Ligand Cooperative Complex Catalyzed Alcohol Dehydrogenative Coupling Reactions

Iron Catalyzed Synthesis of Pyrimidines Under Air

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