Diastereoselective Ullmann Coupling to Bishelicenes by Surface Topochemistry

Mairena, Anaïs; Wäckerlin, Christian; Wienke, Martin; Grenader, Konstantin; Terfort, Andreas; Ernst, Karl‐Heinz

doi:10.1021/jacs.8b10059

Cited by 29 publications

(29 citation statements)

References 38 publications

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“…Beyond the relatively weak supramolecular (non-covalent) self-assembly, recent developments in on-surface synthesis 13–15 pave the way to study chemical reactions between chiral molecules to produce stable chiral products on surfaces. The confinement effect of a 2D surface will kinetically favor either homochiral or heterochiral intermolecular reactions and, as a result, the reactions typically exhibit diastereoselectivity 16–18 .…”

Section: Introductionmentioning

confidence: 99%

Reaction selectivity of homochiral versus heterochiral intermolecular reactions of prochiral terminal alkynes on surfaces

Wang

Huang

et al. 2019

Nat Commun

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Controlling selectivity between homochiral and heterochiral reaction pathways on surfaces remains a great challenge. Here, competing reactions of a prochiral alkyne on Ag(111): two-dimensional (2D) homochiral Glaser coupling and heterochiral cross-coupling with a Bergman cyclization step have been examined. We demonstrate control strategies in steering the reactions between the homochiral and heterochiral pathways by tuning the precursor substituents and the kinetic parameters, as confirmed by high-resolution scanning probe microscopy (SPM). Control experiments and density functional theory (DFT) calculations reveal that the template effect of organometallic chains obtained under specific kinetic conditions enhances Glaser coupling between homochiral molecules. In contrast, for the reaction of free monomers, the kinetically favorable reaction pathway is the cross-coupling between two heterochiral molecules (one of them involving cyclization). This work demonstrates the application of kinetic control to steer chiral organic coupling pathways at surfaces.

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Section: Introductionmentioning

confidence: 99%

Reaction selectivity of homochiral versus heterochiral intermolecular reactions of prochiral terminal alkynes on surfaces

Wang

Huang

et al. 2019

Nat Commun

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“…The chirality is another issue within on‐surface chemistry. Mairena et al. compared the self‐assembled structures of 9,9′‐bisheptahelicene with the same species obtained by on‐surface synthesis via Ullmann coupling, and it indicated that a surface may induce stereoselectivity by topochemistry.…”

Section: Othersmentioning

confidence: 99%

On‐Surface Synthesis of One‐Dimensional Carbon‐Based Nanostructures via C−X and C−H Activation Reactions

Kang

2019

ChemPhysChem

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The past decades have witnessed the emergence of lowdimensional carbon-based nanostructures owing to their unique properties and various subsequent applications. It is of fundamental importance to explore ways to achieve atomically precise fabrication of these interesting structures. The newly developed on-surface synthesis approach provides an efficient strategy for this challenging issue, demonstrating the potential of atomically precise preparation of low-dimensional nanostructures. Up to now, the formation of various surface nanostructures, especially carbon-based ones, such as graphene nanoribbons (GNRs), kinds of organic (organometallic) chains and films, have been achieved via on-surface synthesis strategy, in which in-depth understanding of the reaction mechanism has also been explored. This review article will provide a general overview on the formation of one-dimensional carbon-based nanostructures via on-surface synthesis method. In this review, only a part of the on-surface chemical reactions (specifically, CÀ X (X=Cl, Br, I) and CÀ H activation reactions) under ultra-high vacuum conditions will be covered. CÀ X and CÀ H Activation of sp-CarbonOn-surface dehalogenative/dehydrogenative homocoupling reactions of precursors functionalized with alkynyl groups have manifested great potential for the fabrication of low-dimensional carbon-based nanostructures involving acetylenic scaffolds, such as carbyne, graphyne and graphdiyne. Sun [8] et al. reported the successful formation of one-dimensional wires with acetylenic scaffolding via on-surface CÀ Br activation of sphybridized carbon atoms. They designed and synthesized the precursor 4,4'-di(bromoethynyl)-1,1'-biphenyl (bBEBP), and then deposited it on Au(111) substrate at RT. After annealing tõ 320 K, one-dimensional chains were formed on the surface. These chains were composed of two kinds of alternating protrusions. Thus, an organometallic chain structure combined with CÀ AuÀ C was proposed (as shown in Figure 1a), with the DFT model being in good agreement with the STM image. Further annealing to~425 K leaded to Au atoms released from the organometallic chains, and consequently, CÀ C coupled molecular chains with acetylenic linkages were obtained (as shown in Figure 1b). The disappearance of dot protrusions between biphenyl groups can be observed from the STM images. Additionally, the feasibility to incorporate acetylenic scaffoldings into two-dimensional networks was also be demonstrated in this work. Liu et al. analogously synthesized graphdiyne zigzag chains and macrocycles. Statistical results showed that macrocycles were preferred to form in low coverage of organometallic intermediates. [9] These works act as a supplement to our understandings of on-surface dehalogenative homocoupling reactions, and moreover, make CÀ X activation of sp-hybridized carbon a suitable strategy to synthesize highquality nanostructures with acetylenic linkages.Glaser coupling, discovered by Glaser [10] in 1869, can also be applied to the preparation of chain structures...

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“…Pioneering work from De Schryver and coworkers reported on the conservation of adsorption-induced chirality from self-assembled domains of diacetylene molecules to homochiral polymeric lattices, 20 as recently did Chi and coworkers using alkylated benzenes. 21 Focusing on intrinsic molecular chirality (rather than adsorption-induced), particularly noteworthy is the use of helical aromatic molecules (so-called helicenes) to study the diastereoselective formation of helical dimers [22][23][24] or the transmission from the helical chirality of the molecular precursors to the planar chirality (prochirality) of nanographene adsorbates through a sequence of single-molecule reactions. 25 However, no studies have yet reported e.g.…”

Section: Introductionmentioning

confidence: 99%

Transferring axial molecular chirality through a sequence of on-surface reactions

et al. 2020

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Diastereoselective Ullmann Coupling to Bishelicenes by Surface Topochemistry

Cited by 29 publications

References 38 publications

Reaction selectivity of homochiral versus heterochiral intermolecular reactions of prochiral terminal alkynes on surfaces

Reaction selectivity of homochiral versus heterochiral intermolecular reactions of prochiral terminal alkynes on surfaces

On‐Surface Synthesis of One‐Dimensional Carbon‐Based Nanostructures via C−X and C−H Activation Reactions

Transferring axial molecular chirality through a sequence of on-surface reactions

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