Doppelhelicales Octaphenylen

Abstract

Durch symmetrische Anellierung von zwei funktionalisierten Tetra‐o‐phenylenen wurde doppelhelicales Octaphenylen 1 mit einer 360°‐Windung der Doppelhelix hergestellt. Solche π‐konjugierten Systeme mit intrinsischer Chiralität sind für die Entwicklung einer neuen Generation organischer Materialien von Interesse.

Annelated Heptathiophene: A Fragment of a Carbon–Sulfur Helix

“…As the chirality is introduced only in the final annelation step, the stereochemical problems of racemic synthesis are avoided. [10] In the first iteration, 4,4'-dibromo-3,3'-bithienyl (2) is prepared from 3,4-dibromothiophene by a mono Li/Br exchange, as previously reported. [11] The two most acidic apositions in 2 are TMS-protected to give 3.…”

“…However, as the tetrafunctionalized module 1 is chiral, it would be more efficient to use a single enantiomer of 1 (rather than its racemate) as the starting material. [10] . Towards the DRED of Resin-Supported Combinatorial Libraries: A Non-Invasive Methodology Based on Bead Self-Encoding and Multispectral Imaging** Hicham Fenniri,* Hartmut G. Hedderich, Kenneth S. Haber, Jihane Achkar, Brian Taylor, and Dor Ben-Amotz Combinatorial synthetic methods allow for the preparation of large arrays of compounds as mixtures or individual entities.…”

Chiral Carbon‐rich Macrocycles and Cyclophanes

“…Marsella's work in this area with polythiophenes coincided with that of Rajca and coworkers which focused on polyphenylenes [50]. Beginning with dibromide 118, lithium-halogen exchange followed by oxidative coupling led to the formation of helical monomer 119 in 69% yield (Scheme 6.18).…”

Asymmetric Synthesis of Chiral Tetraphenylenes

“…Meanwhile the biaryl moieties in tetraphenylenes provide intriguing possibilities for the design of novel ligands for asymmetric synthesis. Examples of tetraphenylenes include the chiral rod 4, [9] planarized tetraphenylene 5 (a fragment of a two-dimensional graphene-like carbon sheet and building block for helical stacks of carbotetranions), [10] the conjugated double helix 6 (a fragment of a Rileys "threedimensional graphite"), [11,12] and ligand 7 which is used for enantioselective hydrogenation (Figure 3). [9] However, applications of tetraphenylenes are rather limited, primarily because of the difficulty in obtaining the chiral tetraphenylene core, especially by asymmetric synthesis or by resolution.…”