Synthesis of Co-oligomers of Thiophene Derivatives from Oligoynes via Zirconacyclopentadiene

Abstract

For the formation of oligothiophenes or thiophene cooligomers, a preconnected method using zirconacyclopentadienes was demonstrated. Oligoynes of 4,4-bis(butoxymethyl)-1,6-heptadiyne linked through bithiophene were prepared where all components and diyne moieties were connected in advance before converting to zirconacyclopentadiene-containing precursors. Treatment of the reactive zirconacyclopentadienes in the preconnected precursors with acid, dimethyl acetylenedicarboxylate or sulfur monochloride afforded different oligothiophenes or thiophene co-oligomer derivatives.Oligomers of thiophene or co-oligomers of thiophene with other aromatic components have attracted much attention in relevance to electronic organic materials.1 Synthetic methodology of these oligomers or co-oligomers is an interesting topic. The most general conventional method is the connection of separate components in the presence of a catalytic or equivalent amount of metal compounds as shown in Scheme 1.2 Previously our group and others have demonstrated a Zr-mediated method which involves the conversion of the zirconacyclopentadiene moiety in the precursors into some component as shown in Scheme 1. 3 We have reported Ni-catalyzed polymerization of dibromoterphenyl units. 3a The dibromoterphenyl unit was prepared by this zirconium-mediated method. For the formation of the phenylene copolymers, Tilley and co-workers have reported a method via zirconium-containing phenylene precursors which were prepared by coupling of phenyl-bridged diyne units on zirconium (Scheme 2).3b Herein, we would like to report a novel method for preparation of zirconium-containing precursors using a preconnected method (Scheme 2) for constructing oligomers of thiophene or co-oligomers of thiophene and other conjugated fragments. The preconnected method helped to produce a welldefined conjugated backbone with complete regioselectivity of zirconacyclopentadienes. This is in sharp contrast to a coupling method on zirconium which gives a mixture of several components and regioisomers.Preconnected oligodiynes were prepared by the Sonogashira Hagihara coupling of a terminal diyne and bromo bithiophene. 2,2¤-Bithiophene was chosen as an oligothiophene and 4,4-bis(butoxymethyl)-1,6-heptadiyne as a terminal diyne unit. By careful control of the equivalent ratio of bromo substrate and diyne, oligodiyne 1a, 1b, and 1c were prepared in 83%, 85%, and 64% yields, respectively (Scheme 3). 4

Phenyl-capped cyclopenta[c]chalcogenophenes: synthesis, crystal structures, electrochemistry and theoretical insights

“…[6][7][8][9][10][11] Synthesis of cyclopenta[c]chalcogenophene based compounds have remained interesting. [14][15][16][17][18][19] Here we report synthesis of phenyl capped cyclopenta[c]chalcogenophenes and a comparative study from the crystal structures, Hirshfeld surface analysis, electrochemistry and DFT study.…”