Catalytic Asymmetric Synthesis of Chiral Covalent Organic Frameworks from Prochiral Monomers for Heterogeneous Asymmetric Catalysis

Abstract

Direct synthesis, postsynthetic modification, and chiral induction have been recognized as three powerful methods to synthesize chiral covalent organic frameworks (CCOFs). However, catalytic asymmetric methodology, as the most important and effective synthetic approach to access chiral organics, has not been enabled for CCOFs synthesis thus far. Herein we report, for the first time, the construction of CCOFs from prochiral monomers via catalytic asymmetric polymerization. The obtained propargylamine-linked CCOFs can be the highly reusable chiral catalysts to promote asymmetric Michael addition reactions. The concept of catalytic asymmetric polymerization might open a new route for constructing the CCOFs that are not possible with the existing CCOF synthetic methods.

Three‐Dimensional Covalent‐Organic Frameworks Loaded with Highly Dispersed Ultrafine Palladium Nanoparticles as Efficient Heterogeneous Catalyst

“…During the last decade, the researchers have witnessed tremendous potential applications of COFs, typically in gas storage and separation, semiconducting device, sensor, energy storage, and drug delivery [10–17] . Besides these applications, due to their modifiable internal surface and highly ordered porous structures, the application as topological heterogeneous catalyst has emerged recently [18–20] . Up to now, many two‐dimensional (2D) COFs with layered structures have been designed and synthesized successfully [21–25] .…”

Advances in Chiral Metal–Organic and Covalent Organic Frameworks for Asymmetric Catalysis

“…Besides the aforementioned three powerful approaches, namely direct synthesis, postsynthetic modification, and chiral induction, a novel method, catalytic asymmetric polymerization, was developed very recently for CCOF synthesis. [72] With CuOTf•toulene/(S,S)-or (R,R)-2,6-bis(4-phenyl-2-oxazolinyl) pyridine [Cu(I)-(S,S)-or Cu(I)-(R,R)-pybox] as the chiral catalyst, two propargylamine-linked CCOFs, denoted as (S)-and (R)-DTP-COFs, were successfully synthesized under ambient conditions via asymmetric catalysis from achiral monomers of 2,5-dimeth-oxyterephthaldehyde, 1,3,5-tris(4-aminophenyl)benzene and phenylacetylene, based on a model asymmetric A 3 -coupling reaction (Figure 11). Both the CCOFs could serve as highly active and stereoselective catalysts for asymmetric Michael addition reactions of cyclohexanone to β-nitrostyrene and its derivatives with yields, ees and drs up to 99%, 99% and 88/12, respectively.…”

“…Both the CCOFs could serve as highly active and stereoselective catalysts for asymmetric Michael addition reactions of cyclohexanone to β-nitrostyrene and its derivatives with yields, ees and drs up to 99%, 99% and 88/12, respectively. In addition, [72] Copyright 2020, American Chemical Society.…”

Asymmetric Organocatalysis with Chiral Covalent Organic Frameworks

“…Recently, Dong et al investigated the acyclic amine-based (R)-DTP-COF 11 as a chiral catalyst into the Michael addition as mentioned above (Figure 5). 27 They elegantly used a more sophisticated C-C bond formation reactionthree-component coupling of an alkyne, an aldehyde, and an amine (A3-coupling)into the construction of COF 11. 46 This is by far the only example of constructing a chiral COF with enantioselective synthesis.…”

“…[18][19][20][21][22] Instead of preparing chiral polymers containing several repeating catalytic units, the use of organized and chiral frameworks in enantioselective catalysis is beginning to be investigated. [23][24][25][26][27][28][29][30][31] These materials, either with post-modified chiral motifs or inherent asymmetric backbones, fulfilled asymmetric organocatalysis in a confined microenvironment that mimics polymeric enzymes or ribozymes and thus may contribute to the efficiency and selectivity improvement during the catalytic process. Besides, they also possess the advantages of polymeric catalysts in terms of stability in aqueous solutions, strong acids, and bases, which make them a better catalyst than natural enzymes.…”