The 18-year-old striker has been the subject of talks for a number of weeks after he impressed by scoring six goals in 32 appearances last season.
The Bundesliga team are understood to have agreed to a transfer fee of £500,000 up front plus add-ons for appearances.
“It’s not just paper talk, they have put a bid in,” Tranmere manager Les Parry told BBC Sport. "I'm not too sure how close it is but it's moving along. They're keen to get him over there and it's a great move.
"If you look back at the number of young players who have had the chance to go abroad to one of the giants of Europe, there's very few English players who have done that. It's a fantastic opportunity for him."