Iminiumkatalyse in einer selbstorganisierten supramolekularen Kapsel: Modulation des Enantiomerenüberschusses

Bräuer, Thomas M.; Zhang, Qi; Tiefenbacher, Konrad

doi:10.1002/ange.201602382

Cited by 36 publications

(1 citation statement)

References 83 publications

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“…Resorcin [4]arenes in general are intensively studied tetrameric resorcinol-based structures with a broad range of useful applications in catalysis and especially in host-guest chemistry, [1] supramolecular containers, [2,3] or even molecular machines. [4] Resorcin [4]arenes offer a broad variety of bowl-or vase-like structural backbones on the road to specifically designed supramolecular structures.…”

Section: Introductionmentioning

confidence: 99%

Mono‐ and Tri‐Functionalization of Trimethylresorcin[4]arenes

et al. 2019

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Section: Introductionmentioning

confidence: 99%

Mono‐ and Tri‐Functionalization of Trimethylresorcin[4]arenes

et al. 2019

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Chirality‐Assisted Synthesis of a Very Large Octameric Hydrogen‐Bonded Capsule

2016

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The strategy of chirality-assisted synthesis, which makes use of enantiomerically pure building blocks that are designed to associate in a single geometric orientation, was applied to synthesize an octameric hydrogen-bonded capsule with a cavity volume of 2300 3 . This cube-shaped capsule forms even host-guest complexes with tetraalkylammonium ions, and accommodates the large tetrahexadecylammonium cation in its cavity. The use of an enantiopure building block was shown to be highly beneficial for capsule formation, whereas its racemate also generates a large amount of illdefined aggregates in solution and crystallizes as a hydrogenbonded network.The synthesis of artificial viral capsids self-assembled from small molecules has attracted considerable interest since the first molecular containers were reported by the groups of Cram [1] and Collet [2] in the mid-1980s. [3] Since then, the size of covalent organic [4] and metal-organic [5] cages has continuously increased, with the largest yet reported reaching a diameter of about 8 nm while partially surrounding an open cavity volume of roughly 160 000 3 . [6] In contrast, the size of closed-shell molecular capsules that spontaneously self-assemble in solution through noncovalent interactions has stagnated since hexameric resorcinarene-and pyrogallolarene-derived capsules were discovered in the late 1990s. [7] Such capsules completely enclose the space defined by their cavity, but with cavity volumes only reaching about 1400 3 they are dwarfed by even the smallest known viruses. As such, the encapsulation of large molecules (e.g., proteins and DNA fragments) by noncovalent capsules remains a long-term objective. [8] One major difficulty in the synthesis of large noncovalently bound capsules arises from the relatively poor directionality of noncovalent interactions which can result in the formation of networks instead of discrete nanosized objects. [9] In this regard, a simple way to reduce the likelihood of network formation is to design small molecules that form dimeric capsules through multiple interactions, and it is therefore not surprising that dimeric capsules [3f, 10] far outnumber tetrameric, [11] pentameric, [12] hexameric, [7a,b, 13] and higher-order capsules.[14] However, a major drawback of this approach is that the size of the molecular units required for the construction of a dimeric capsule increases at the same rate as the targeted capsule itself. From a synthetic point of view, it is far more desirable to use several small components instead of two large ones. The strategy of chirality-assisted synthesis may help solve this problem as the use of enantiopure, inherently chiral building blocks should work against the formation of polymeric materials.[15] Herein we show that this strategy can be exploited to rationally design a small molecule that predictably self-assembles into a hydrogen-bonded capsule with a very large cavity volume.Tris(isatin) 1 (Figure 1 A) was designed by combining a tribenzotriquinacene core [16] with confor...

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Catalysis with Pnictogen, Chalcogen, and Halogen Bonds

et al. 2018

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Halogen-and chalcogen-based s-hole interactions have recently received increased interest in non-covalent organocatalysis.H owever,t he closely related pnictogen bonds have been neglected. In this study,w ei ntroduce conceptually simple,n eutral, and monodentate pnictogenbonding catalysts.S olution and in silico binding studies, together with high catalytic activity in chloride abstraction reactions,yield compelling evidence for operational pnictogen bonds.T he depth of the s holes is easily varied with different substituents.C omparison with homologous halogen-and chalcogen-bonding catalysts shows an increase in activity from main group VII to Vand from row 3to5inthe periodic table.Pnictogen bonds from antimony thus emerged as by far the best among the elements covered,af inding that provides most intriguing perspectives for future applications in catalysis and beyond.

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Iminiumkatalyse in einer selbstorganisierten supramolekularen Kapsel: Modulation des Enantiomerenüberschusses

Cited by 36 publications

References 83 publications

Mono‐ and Tri‐Functionalization of Trimethylresorcin[4]arenes

Mono‐ and Tri‐Functionalization of Trimethylresorcin[4]arenes

Chirality‐Assisted Synthesis of a Very Large Octameric Hydrogen‐Bonded Capsule

Catalysis with Pnictogen, Chalcogen, and Halogen Bonds

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