I have made some reactions with epoxides, generally they are less reactive than for example iodides. If you want to react a epoxide with diethyl malonate under basic conditions you need many hours and heat. You can open epoxides with dialkyllithiocuprates if you use BF3Et2O to activate the epoxide. The question is what coupling you want to do, is it a arylboronic acid and a aryliodide for example I think this would work, I dont se why the epoxide should open.