Studies of the reaction of 3-bromo-2,5-dimethylthiophene 1,1-dioxide with some organocopper reagents

The coupling reactions of some organocopper reagents with 3-bromo-2,5-dimethylthiophene 1,1-dioxide leading to 3-alkyl and 3-aryl substituted 2,5-dimethylthiophene 1,1-dioxides have been found to proceed in high yields (50–100%). The less stable organocopper reagents reacted faster and at lower temperatures than the more stable ones. It is more convenient to use alkylcopper than lithium dialkylcuprate reagents, which give higher yields without side reactions.