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• 3141-26-2 3,4-dibromothiophene 
• 5556-13-8 4,4′-dibromo-3,3′-bithiophene 

Relevant academic research and scientific papers

Thiophene-Based Double Helices: Syntheses, X-ray Structures, and Chiroptical Properties

We demonstrate facile and efficient construction of conjugated double helical ladder oligomers from the saddle-shaped cyclooctatetrathiophene (COTh) building blocks. The key step involves deprotonation of tetra[3,4]thienylene (β,β-COTh) with n-BuLi which displays remarkably high ipsilateral selectivity. Three racemic double helical ladder oligomers, rac-DH-1, rac-DH-2, and rac-DH-3, containing two, three, and five COTh annelated moieties are efficiently synthesized by diastereoselective coupling of the racemic precursors. The X-ray crystallographic studies of rac-DH-1, rac-DH-2 and rac-DH-3 unambiguously revealed that each double helical scaffold has two single helices intertwined with each other via the C-C single bonds. Following removal of TMS groups, double helical ladder oligomer rac-DH-1-D had sufficient solubility to be resolved via chiral HPLC, thus enabling determination of its chirooptical properties such as CD spectra and optical rotation. (+)-DH-1-D has a large barrier for racemization, with lower limit of ΔG? > 48 kcal mol-1, which may be compared to DFT-computed barrier of 51 kcal mol-1. The enantiomers of DH-1-D show 1 order of magnitude stronger chirooptical properties than the carbon-sulfur [7]helicene, as determined by the anisotropy factor g = Δ?/? = -0.039, based on Δ?max = -11 and ? = 2.8 × 102 L mol-1 cm-1 in cyclohexane at 327 nm.

Planar [6]radialenes: Structure, synthesis, and aromaticity of benzotriselenophene and benzotrithiophene

(Figure Presented) Planar, but non-aromatic: The title [6]radialenes, which contain thiophene and selenophene units (see the ORTEP diagrams), can be prepared in a straightforward manner. X-ray crystal structures and the results of theoretical studies show that the central six-membered ring of these compounds, although planar and composed entirely of sp2-hybridized carbon atoms, is completely non-aromatic.

Synthesis of Tetrasilatetrathia[8]circulenes through C-I and C-H Silylation

We have succeeded in the synthesis of various tetrasilatetrathia[8]circulenes with alkyl and aryl groups on the silicon atoms. We also disclosed the effect of phosphine ligands on palladium-catalyzed silylation of tetraiodotetrathienylene and rhodium-cata

Versatile Hydrogen-Bonded Assemblies of Twisted Tetra[3,4]thienylene Tetracarboxylic Acid with Selective Solvent Sorption

We demonstrated versatile hydrogen-bonded assemblies of a twisted πsystem with newly synthesized tetra[3,4]thienylene tetracarboxylic acid ThTCA. Due to its twisted saddle-shaped central πaromatic unit with an anisotropic arrangement of carboxyl units, a variety of dimensional solvate molecular crystals could be obtained, in contrast to typical aromatic carboxylic acid derivatives with low-dimensional assemblies. The versatile molecular assemblies could be converged to ThTCAdesol by desolvation with a simple annealing technique. ThTCAdesol showed selective solvent sorption behavior, which was governed by the solvent association energy and saturated vapor pressure. Especially, ThTCAdesol showed the selective sorption of EtOH, among primary alcohols.

New syntheses of tricyclic thiophenes and cyclic tetrathiophenes using transition-metal-catalyzed cyclization

New synthetic methods for polycyclic thiophenes were developed. Thus, dithienothiophenes, cyclopentadithiophene, silacyclopentadithiophenes, and cyclooctatetrathiophenes were synthesized in moderate to good yields by using the CuCl2-mediated cyclization of organocopper(I) and organozinc intermediates prepared from dilithio-derivatives with CuCN or ZnCl2, respectively. A direct cyclization of bromothiophene derivatives with hexamethylditin in the presence of tetrakis(triphenylphosphine)palladium(0) also gave dithienothiophenes, cyclopenta-dithiophenes, and silacyclopentadithiophenes in good yields.

Research on carbon-carbon coupling reactions of haloaromatic compounds mediated by zerovalent nickel complexes. Preparation of cyclic oligomers of thiophene and benzene and stable anthrylnickel(II) complexes

Dehalogenative carbon-carbon coupling reactions of 3,4-dibromothiophene, 1,2-dihalobenzenes and 9-bromoanthracene using zerovalent nickel complexes as a dehalogenating reagent produced respectively cyclotetrathiophene, triphenylene and 9,9'-bianthracene in good yields.However, two extremely stable arylnickel(II) complexes, Ni(10-X-9-anthryl)X(PPh3)2 (X = Br, Cl), where the 10-C-X bond in the anthryl groups was inert against excess Ni0 complexes, were obtained by oxidative addition of 9,10-dihaloanthracenes to the Ni0 complexes.Under similar reaction conditions 9,10-dihaloanthracenes did not undergo carbon-carbon coupling reactions.