Ring-opening reactions. Part 16. Ring-opening of 2,5-dimethoxy-3-thienyl-lithium and some related compounds

Evidence is presented indicating that 2,5-dimethoxythiophen is metallated in the β-position by butyl-lithium to give 2,5-dimethoxy-3-thienyl-lithium, which subsequently undergoes ring-opening. By the use of 2 equiv. of butyl-lithium followed by dimethyl sulphate, it was possible to isolate 1-methylthio-octa-1,3-diyne as the main product.