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• 17965-59-2 3,3'-Dibromo-2,2'-dithienylmethane 

Relevant academic research and scientific papers

Efficient construction of biaryls and macrocyclic cyclophanes via electron-transfer oxidation of Lipshutz cuprates

An efficient method for the homocoupling of aryl halides by electron-transfer oxidation of Lipshutz cuprates (Ar2Cu(CN)Li 2) with organic electron acceptors is disclosed. Thus, various types of Lipshutz cuprates are prepared by successive treatment of aryl or heteroaryl bromides with tert-butyllithium and CuCN. The electron-transfer oxidation of Lipshutz cuprates with p-benzoquinones proceeds smoothly to afford the corresponding homocoupling products in moderate to good yields. Furthermore, it can be applied to the construction of either thiophene- or benzene-fused 10-membered ring cyclophanes. For the synthesis of 10-membered cyclophanes, the linear C-Cu-C structure of Lipshutz cuprates should be maintained in the dimetallacyclic intermediates, producing the large ring cyclophanes efficiently. The X-ray analysis of the cyclophanes reveals that the difference in the bridging atoms results in the different conformations of the macrocyclic rings. Thus, the silicon-bridged cyclophane 5a adopts a D2-symmetric structure with a twisted rhombic arrangement of four thiophene rings, whereas the methylene- and oxygen-bridged cyclophanes 5b and 5c possess C2h- and C2-symmetric structures with chair- and boatlike conformations, respectively. The 1H NMR spectrum of C2-symmetric 5c is temperature-dependent, and the activation energy (ΔG?) for the conformational change is 10.1 kcal/mol.

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.

Synthesis of dithienothiophenes, cyclopentadithiophene and silacyclopentadithiophenes using palladium catalyzed cyclization

The intramolecular cyclization of bromothiophene derivatives with hexamethylditin in the presence of tetrakis(triphenylphosphine)palladium(O) gave dithienothiophenes, cyclopentadithiophene, and silacyclopentadithiophenes in moderate to good yields.