Alkylated 2,2′-bithiophenes and 2-phenylthiophenes in the composition of pyrolysis products of high-sulfur kerogen
摘要:
Compounds from the 5-n-alkyl-2,2'-bithiophene, 5-n-alkyl-5'-methyl-2,2'-bithiophene, 5-n-alkyl-2-phenylthiophene, and 5-n-alkyl-2-o-tolylthiophene homologous series were synthesized to prove their presence in the pyrolysis products of sulfur-rich kerogen. A study of the pyrolysis products of sulfur-vulcanized polybutadiene confirmed that these compounds can be formed via the thermal transformation of n-alkyl polysulfur-bound fragments of sulfur-rich kerogen. The earlier proposed scheme that assumes the dependence of the composition of the pyrolysis products of sulfur-rich kerogen on its saturation with sulfide bridges was experimentally corroborated.
Ligand-less palladium-catalyzed direct 5-arylation of thiophenes at low catalyst loadings
作者:Julien Roger、Franc Požgan、Henri Doucet
DOI:10.1039/b819912d
日期:——
Ligand-less Pd(OAc)2 provides a very efficient catalyst for the direct5-arylation of thiophenederivatives. With this catalyst, a low palladium concentration (0.1–0.001 mol%) should be employed in order to obtain high yields of coupling products. At higher concentrations a fast formation of inactive “Pd black” generally occurs. Substrates/catalysts ratios up to 100000 can be employed with the most
Palladium associated with cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane (Tedicyp) was found to promote the direct 2-arylation of a variety of thiophene derivatives via CH functionalisation in good yields using very lowcatalystloadings. Electron-deficient, electron-excessive or sterically-congested aryl bromides are tolerated. Moreover, several substituents on the aryl bromide
A new ferrocenyl triphosphane ligand associated to palladium was found to be an efficient catalyst for the direct coupling of highly congested, functionalised aryl bromides with a variety of heteroarenes. These coupling reactions can generally be performed by using a low‐loading (0.1–0.5 mol %) of the catalyst. The present protocol tolerates important and useful functional groups, which allows for