Kirkland & Ellis, Bredin Prat, Darrois Villey Maillot Brochier, Jones Day, Freshfields Bruckhaus Deringer, Latham & Watkins and DLA Piper are among the law firms advising on "exclusive negotiations" for a deal in which French drugmaker Sanofi would sell a controlling stake in its consumer health care unit to the U.S. private equity company Clayton Dubilier & Rice.