Stille coupling thiophenes

Copolymer 459, prepared by Stille coupling of dibromophenylene with 2,5-Mv(tributyl-stannyl)thiophene, represents another example of a phenylene-u/t-thiophene backbone, where the substituted phenylene unit forms an oligophenylene vinylene fragment that is not in the main conjugation chain [561]. A PLED fabricated with this polymer (ITO/459/A1) emitted green light (520 nm) with a turn-on voltage of ca. 9.5 V, but no other data on luminance or efficiency of the device were reported (Chart 2.111). 

A low band-gap (Eg 1.6 eV) conjugated thiophene copolymer 468 with pyrrole and BT units was synthesized by Stille coupling [568]. They showed emission in the NIR region (AEL 800 nm) with turn-on voltage below 4 V but with very low efficiency (Chart 2.113). 

PPh3)4Pd(0) in boiling toluene to yield 371. Similarly, 369 is accessible by a Stille coupling of 367 with 2-stannyl substituted thiophene (2005BMCL5003). 

The third-generation dendrimer palladium complex (31, containing 24 PdC groups) was applied in the Stille coupling of methyl-2-iodobenzoate with 2-(tributyl-stannyl)thiophene in DMF (Scheme 10 lmol% catalyst). In contrast to what was observed with the monomer (PPh3)2PdCl2, no palladium metal formation was... 

The related polythiophene 64 has been produced in 63% yield by a Stille coupling from 2-(tributylstannyl)-3,4-(ethylenedioxy)thiophene and 2,6-dibromo-4f/-cyclopenta[2,l- 3,4- ]dithiophen-4-one catalyzed by PdCl2(PPh3)2 or Pd(PPh3)4 in refluxing toluene <2004CM3667>. 

The arylation of support-bound arenes has mainly been performed using the Suzuki and Stille coupling reactions. Both reactions proceed smoothly with arenes and het-eroarenes such as furans, thiophenes, or pyridines. Examples of the arylation of het-eroarenes are presented in Chapter 15. 

Thiophenes have been prepared on insoluble supports mainly by arylation or viny-lation of halothiophenes and thienylstannanes (Table 15.10). Heck, Suzuki, and Stille couplings with thiophenes usually proceed as smoothly as those with substituted benzenes, and arylations or vinylations of thiophenes have often been used as examples to illustrate new conditions for the realization of these coupling reactions on solid phase. 

Stable polythiophene semiconductors 237 incorporating the thieno[2,3-fc]thiophene ring system were synthesized by Stille coupling of 5,5 -dibromo-4,4 -dialkyl-2,2 -bithiophene 235 with thieno[2,3-fc]thiophene-2,5-diylbis(trimethystannane) 236 (Scheme 48). The polymers 237 described showed both good charge carrier mobility and stability to ambient air and light [62],... 

This concept has been extended to oligothiophenes as well. A series of oligothiophenes, containing two to six thiophene units, and entirely surrounded by bicyclooctene frameworks have been constructed using a combination of Stille coupling (see Section 3.10.2.11.2) and oxidative coupling <1996CHEC-II(2)491>. 

STILLE COUPLINGS CATALYZED BY PALLADIUM-ON-CARBON WITH CDPPER(I) IODIDE AS A COCATALYST SYNTHESIS OF 2-(4 -ACETYLPHENYL)THIOPHENE. 

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