Reaction of Tri-2-thienylmethyllithium with Alkyl Halides. Substitution on Carbanion Center vs. Thiophene Ring

Article abstract of DOI:10.1246/cl.1992.703

Tri-2-thienylmethyllithium, produced by treatment of tri-2-thienylmethane with butyllithium in the presence of N,N,N',N'-tetramethylethylenediamine at -78 deg C in tetrahydrofuran, reacts with primary alkyl halides to give the alkylated products on the carbanion center nearly quantitatively, while the reaction with secondary and tertiary alkyl halides affords not only the substitution products at the carboanion center but also those at the 3-position of the thiophene ring.