McMURRY COUPLING OF DIFORMYLDITHIENYLACETYLENE: SYNTHESIS OF [24]-, [36]-, AND [48]ANNULENES COMPOSED OF THIOPHENE, ACETYLENE, AND ETHYLENE UNITS

摘要

The reaction of diformyldithienylacetylene 4 with a McMurry reagent prepared from TiCl4, Zn, and pyridine in THF afforded 24π-dimer lb (15%), 36π-trimer 2b (13%), and 48π-tetramer 3b (6%). From X-ray analysis, lb adopts a twisted conformation, although the 1H NMR spectrum of lb shows a symmetrical structure owing to a rapid conformational change in solution. Absorption and emission spectra, redox properties, and electric conductivities of lb-3b were measured in order to study the structure-property relationship of these macrocyclic systems.