RESUMO
A regioregular organometallic polymer possessing titanacyclopentadiene units in the main chain, which was obtained by the reaction of terminal diyne and a low-valent titanium complex, was subjected to the reaction with dichlorophosphines to give π-conjugated polymers with phosphole or phosphole oxide units in the main chain. For example, a phenylphosphole-containing polymer was obtained in 76% yield by the reaction with dichlorophenylphosphine, whose number-average molecular weight (Mn) and molecular weight distribution (Mw/Mn) were estimated to be 6100 and 1.9, respectively, by GPC. The polymer was found to have an extended π-conjugated system, and its lowest unoccupied molecular orbital (LUMO) energy level was remarkably low (-3.28 eV) as supported by its UV-vis absorption spectrum and cyclic voltammetric (CV) analysis. Also, the polymer exhibits orange photoluminescence with an emission maximum (Emax) of 595 nm and a quantum yield (Φ) of 0.10.
RESUMO
Silylboronic esters bearing a dialkylamino group on the silicon atoms reacted with 1,3-dienes in the presence of a palladium catalyst to give silacyclopent-3-enes (i.e., 2,5-dihydrosiloles) in high yields via efficient silylene transfer from the silylboronic ester to the 1,3-dienes. The [4 + 1] cycloaddition was applicable to the parent 1,3-butadiene and various mono-, di-, and trisubstituted 1,3-dienes having silyloxy, cyano, and ester groups. Stereospecific ring formation took place in the reaction with either stereoisomer of 5,7-dodecadiene: the (E,E)-diene gave the cis product, whereas selective formation of the trans product was observed in the reaction of the isomeric (E,Z)-diene. The [4 + 1] cycloaddition followed by dehydrogenation with DDQ or chloranil afforded 2,4- and 2,5-diarylsiloles.
