SYNTHESIS AND (13)C NMR CHARACTERIZATION OF SOME π-EXCESSIVE HETEROPOLYAROMATIC COMPOUNDS

Article abstract of DOI:10.1016/S0040-4020(01)96555-X

Several ?-excessive heteropolyaromatic compounds, which contain furan and thiophen ring and are possible antifungal agents, have been synthesized in good yields according to two general methods.The first method has been used to prepare compounds possessing thiophens linked by their 2- and 5-positions, such as the ter-aryls 2b, 2d and 2a.Two precursors of these compounds have been obtained either by the Glaser reaction, or using a novel Pd-mediated reaction.The second method, which consists of the Ni- or Pd-catalyzed heteroarylation of heteroarene halides via cross-coupling with heteroaryl Grignard reagents or zinc halides, has been used to prepare the bi-aryls 1a-e, which contain two heteroaromatic units, and the ter-aryl 2c.Compound 1e has been also prepared starting from 2-(2-thienyl)furan (1c) by selective lithiation, followed by bromination.The (13)C NMR signals of 1a-e and 2a-d have been assigned on the basis of the literature data and by relaxation measurements.Relaxation data have been also used to obtain qualitative informations on the conformational equilibria of the bi-aryls 1a, 1c and the ter-aryls 2a-d.