They’re all together in “Avengers: Infinity War”; Iron Man. Spider-Man. Guardians of the Galaxy. Doctor Strange. It is the culmination of the entire Marvel Cinematic Universe as started in 2008 with Iron Man.
Avengers: Infinity War hits theaters in May of 2018.
Marvel’s just-released featurette from January 23, 2017 — the first day of shooting:
— Marvel Studios (@MarvelStudios) February 11, 2017