One-pot amination of aldehydes and ketones over heterogeneous catalysts for production of secondary amines

Dibenzylamine motifs are an important class of crucial organic compounds and are widely used in fine chemical and pharmaceutical industries. The development of the efficient, economical, and environmentally friendly synthesis of amines using transition metal-based heterogeneous catalysts remains both desirable and challenging. Herein, we prepared the covalent organic framework (COF)-supported heterogeneous reduced COF-supported Pd-based catalyst and used it for the one-pot reductive amination of aldehydes. There are both Pd metallic state and oxidated Pdσ+ in the catalysts. Furthermore, in the presence of the reduced COF-supported Pd-based catalyst, many aromatic, aliphatic, and heterocyclic aldehydes with various functional groups substituted were converted to their corresponding amines products in good to excellent selectivity (up to 91%) under mild reaction conditions (70 °C, 2 h, NH3, 20 bar H2). This work expands the covalent organic frameworks for the material family and its support catalyst, opening up new catalytic applications in the economical, practical, and effective synthesis of secondary amines.

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Amine-linked Covalent Organic Frameworks as a Powerful Platform for Post-Synthetic Modification: Structure Interconversion and Combined Linkage- and Pore-Wall-Modification

10.26434/chemrxiv.12985907.v1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Lars Grunenberg ◽

Gökcen Savasci ◽

Maxwell Terban ◽

Viola Duppel ◽

Igor Moudrakovski ◽

...

Keyword(s):

Heterogeneous Catalysts ◽

Hydrolytic Stability ◽

Pore Wall ◽

Single Step ◽

Synthetic Methods ◽

Secondary Amines ◽

Covalent Organic Frameworks ◽

One Pot ◽

Surface Areas ◽

Novel Strategy

<div>Covalent organic frameworks have emerged as a powerful synthetic platform for installing and interconverting dedicated molecular functions on a crystalline polymeric backbone with atomic precision. Here, we present a novel strategy to directly access amine-linked covalent organic frameworks, which serve as a scaffold enabling pore-wall modification and linkage-interconversion by new synthetic methods based on Leuckart-Wallach reduction with formic acid and ammonium formate. Frameworks connected entirely by secondary amine linkages, mixed amine/imine bonds, and partially formylated amine linkages are obtained in a single step from imine-linked frameworks, or directly from corresponding linkers in a one-pot crystallisation-reduction approach. The new, 2D amine-linked covalent organic frameworks, rPI-3-COF, rTTI-COF, and rPy1P-COF, are obtained with high crystallinity and large surface areas. Secondary amines, installed as reactive-sites on the pore wall, enable further post-synthetic functionalisation to access tailored covalent organic frameworks, with increased hydrolytic stability, as potential heterogeneous catalysts.</div>

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Supported bimetallic nano-alloys as highly active catalysts for the one-pot tandem synthesis of imines and secondary amines from nitrobenzene and alcohols

Catalysis Science & Technology ◽

10.1039/c6cy00425c ◽

2016 ◽

Vol 6 (14) ◽

pp. 5473-5482 ◽

Cited By ~ 25

Author(s):

Meenakshisundaram Sankar ◽

Qian He ◽

Simon Dawson ◽

Ewa Nowicka ◽

Li Lu ◽

...

Keyword(s):

Heterogeneous Catalysts ◽

Secondary Amines ◽

One Pot ◽

Benzylic Alcohols ◽

One Pot Synthesis ◽

Highly Active ◽

The One ◽

Tandem Synthesis

All-in-one: supported nanoalloys as efficient heterogeneous catalysts for the one-pot synthesis of imines and secondary amines directly from nitrobenzene and benzylic alcohols using a hydrogen auto transfer strategy.

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Amine-linked Covalent Organic Frameworks as a Powerful Platform for Post-Synthetic Modification: Structure Interconversion and Combined Linkage- and Pore-Wall-Modification

10.26434/chemrxiv.12985907 ◽

2020 ◽

Author(s):

Lars Grunenberg ◽

Gökcen Savasci ◽

Maxwell Terban ◽

Viola Duppel ◽

Igor Moudrakovski ◽

...

Keyword(s):

Heterogeneous Catalysts ◽

Hydrolytic Stability ◽

Pore Wall ◽

Single Step ◽

Synthetic Methods ◽

Secondary Amines ◽

Covalent Organic Frameworks ◽

One Pot ◽

Surface Areas ◽

Novel Strategy

<div>Covalent organic frameworks have emerged as a powerful synthetic platform for installing and interconverting dedicated molecular functions on a crystalline polymeric backbone with atomic precision. Here, we present a novel strategy to directly access amine-linked covalent organic frameworks, which serve as a scaffold enabling pore-wall modification and linkage-interconversion by new synthetic methods based on Leuckart-Wallach reduction with formic acid and ammonium formate. Frameworks connected entirely by secondary amine linkages, mixed amine/imine bonds, and partially formylated amine linkages are obtained in a single step from imine-linked frameworks, or directly from corresponding linkers in a one-pot crystallisation-reduction approach. The new, 2D amine-linked covalent organic frameworks, rPI-3-COF, rTTI-COF, and rPy1P-COF, are obtained with high crystallinity and large surface areas. Secondary amines, installed as reactive-sites on the pore wall, enable further post-synthetic functionalisation to access tailored covalent organic frameworks, with increased hydrolytic stability, as potential heterogeneous catalysts.</div>

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Cross-Linked Cyclodextrins Bimetallic Nanocatalysts: Applications in Microwave-Assisted Reductive Aminations

Molecules ◽

10.3390/molecules25020410 ◽

2020 ◽

Vol 25 (2) ◽

pp. 410

Author(s):

Emanuela Calcio Gaudino ◽

Elisa Acciardo ◽

Silvia Tabasso ◽

Maela Manzoli ◽

Giancarlo Cravotto ◽

...

Keyword(s):

Reductive Amination ◽

Nitro Compounds ◽

Secondary Amines ◽

Cross Linking ◽

Reaction Conditions ◽

One Pot ◽

Microwave Assisted ◽

Aldehydes And Ketones ◽

Bimetallic Nanocatalysts ◽

High Yields

The optimization of sustainable protocols for reductive amination has been a lingering challenge in green synthesis. In this context, a comparative study of different metal-loaded cross-linked cyclodextrins (CDs) were examined for the microwave (MW)-assisted reductive amination of aldehydes and ketones using either H2 or formic acid as a hydrogen source. The Pd/Cu heterogeneous nanocatalyst based on Pd (II) and Cu (I) salts embedded in a β-CD network was the most efficient in terms of yield and selectivity attained. In addition, the polymeric cross-linking avoided metal leaching, thus enhancing the process sustainability; good yields were realized using benzylamine under H2. These interesting findings were then applied to the MW-assisted one-pot synthesis of secondary amines via a tandem reductive amination of benzaldehyde with nitroaromatics under H2 pressure. The formation of a CuxPdy alloy under reaction conditions was discerned, and a synergic effect due to the cooperation between Cu and Pd has been hypothesized. During the reaction, the system worked as a bifunctional nanocatalyst wherein the Pd sites facilitate the reduction of nitro compounds, while the Cu species promote the subsequent imine hydrogenation affording structurally diverse secondary amines with high yields.

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