After going through a revolving door of leading men, Warner Bros. and Dark Castle are now negotiating with “300″ star Gerard Butler to topline Albert Hughes’ action pic “Motor City.”Dominic Cooper was originally slated to star before scheduling conflicts forced producers to move on to Jake Gyllenhaal, who had similar issues, prompting producers to turn to Butler. If a deal makes, Butler would play a felon who, after being released from prison, begins tracking down the men who framed him. Amber Heard and Gary Oldman are already on board to co-star in the Chad St. John-scripted pic. Joel Silver is producing through his Dark Castle shingle along with Andrew Rona. Ethan Erwin and Doug Urbanski are exec producing. Butler, who next stars in Millennium Films’ “Playing the Field,” recently signed on to star in the company’s White House-set action pic “Olympus.” He’s repped by CAA and Alan Siegel Entertainment.