Where did Methadone come from?

Where did methadone come from?
Methadone Hydrochloride is an opioid (a synthetic opiate) that was originally synthesised by German pharmaceutical companies during the Second World War.
It was first marketed as 'Dolophine' (possibly to honor Adolph Hitler) and was used as an analgesic (a painkiller) for the treatment of severe pain. It is still occasionally used for pain relief.
Methadone is now primarily used today for the treatment of narcotic addiction. The effects of methadone are longer-lasting than those of morphine-based drugs. Methadone's effects can last up to 24 hours, thereby permitting administration only once a day in heroin detoxification and maintenance programs.