When Gian Gastone died in 1737 , Francis Stephen 's envoy offered Anna Maria Luisa the position of regent of Tuscany but she declined . Gian Gastone died from `` an accumulation of diseases '' on 9 July 1737 , surrounded by prelates and his sister . Anna Maria Luisa was offered a nominal regency by the Prince de Craon , the Grand Duke 's envoy , until Francis III could arrive in Florence , but declined .