Here is a couple of links to distilleries using green malted corn for their "single malt" whiskeys.
http://chuckcowdery.blogspot.com/2010/03/geek-out-warning-green-corn-malt.html
https://thewhiskeywash.com/whiskey-styles/american-whiskey/an-american-single-malt-whiskey-made-from-corn/