SYNTHESIS OF ALPHA-THIOPHENE OLIGOMERS VIA ORGANOTIN COMPOUNDS

A versatile synthetic route involving the use of organotin compounds h as been applied for the preparation of functionalized oligothiophenes. Thus, substituted alpha-bithiophenes have been synthesized via the co upling reaction of 2-bromothiophenes with 2-trimethylstannylthiophene. The latter reagent couples with 2,5-dibromothiophenes to give the alp ha-terthiophenes which are also accessible through the reaction of 5-t rimethylstannyl-alpha-bithiophene with 2-bromothiophenes. 2,5-Bis(trim ethylstannyl) thiophene and 5,5'-bis(trimethylstannyl)-alpha-bithiophe ne react with 2-bromothiophenes to give alpha-terthiophenes and alpha- quaterthiophenes, respectively. alpha-Quateahiophene is also produced via the reaction of 5-trimethylstannylthiophene with 5,5'- dibromo-alp ha-bithiophene. The coupling reaction of 5-trimethylstannyl-alpha-bith iophene with 2,5-dibromothiophene affords the alpha-quinquethiophene. The structures of the new compounds were confirmed by elemental analys is, Mass spectrometry, H-1- and C-13-NMR spectral data.