The board of the French drug giant Sanofi has fired CEO Christopher A. Viehbacher. The board made clear its problems lay not with Viehbacher’s strategy but with disagreements about management style. Viehbacher took the helm at Sanofi in 2008 and proceeded to turn around a business facing patent losses on top-selling products. But after that transformation, Viehbacher’s management style “was not adequate,” Serge Weinberg, chairman of Sanofi’s board, told investors last week. Weinberg, who will serve as interim CEO, says the company is looking outside its walls for a new CEO.