Patent ID: 8436208

Claim:
A process for the preparation of a substituted 2,2′-dithiophene, which process comprises the steps a) reaction of a compound of the formula wherein Hal stands for hydrogen or halogen, R1 and R1′ independently are hydrogen or a substituent, n ranges from 0 to 6; Y, if present, is substituted or unsubstituted phenylene, thiene, 1,2-ethylene, or is 1,2-ethinylene; R2 and R2′ independently are hydrogen or are selected from C 1 -C 25 alkyl, C 3 -C 12 cycloalkyl, C 4 -C 25 aryl, C 5 -C 25 alkylaryl or C 5 -C 25 aralkyl, each of which is unsubstituted or substituted, and R2 and/or R2′ may also be halogen; with a lithium organic compound; b) optional exchange of lithium against another metal selected from Mg, Zn and Cu by reaction with a metal salt or metal organic compound; followed by c) reaction of the metallated intermediate obtained in step (a) or (b) with an electrophile, which is CO 2 , an aldehyde (addition reaction), a compound Y′—R17 or Y′—R18-Z (substitution reaction), where R17 is an acyl or silyl residue, R18 is selected from CO, CO—CO, where R4, R5, and R10 are selected from C 1 -C 25 alkyl, C 3 -C 12 cycloalkyl, C 4 -C 25 aryl, C 5 -C 25 alkylaryl or C 5 -C 25 aralkyl, each of which is unsubstituted or substituted; Y′ and Z′ are suitable leaving groups allowing for a reaction with the metal thienyl intermediate formed in step (a) or (b); and optionally d) modification of the product obtained in step (c), by introducing one or more conjugating moieties Y as defined above, ring closure between monovalent residues R17, exchange or extension of functional groups or substituents in R17 or R18.