His most famous pupils were Hector Berlioz , Ambroise Thomas and Charles Gounod . From the beginning of 1818 , he taught composition at the Conservatoire , where over the years he had for pupils Hector Berlioz , Ambroise Thomas , Charles Gounod , Louis-D Ã sirÃ Besozzi and Antoine FranÃ ois Marmontel .