 French healthcare company Sanofi SA has agreed to buy U.S. company Principia Biopharma Inc for around 3.7 billion, the companies said on Monday, strengthening Sanofis presence in research and development RD areas. Sanofi will buy the outstanding shares of Principia for 100 per share in cash, according to the joint statement, representing an aggregate equity value of around 3.68 billion on a fully diluted basis and a premium of 10 to Principia Biopharmas stock closing of 90.74 on Aug. 14. Sanofi said the acquisition of Principia Biopharma, which develops therapies for serious immune diseases, would strengthen its research capabilities in areas such as autoimmune and allergic diseases. 