The England international is a target for Manchester United but they are unwilling to pay the Bundesliga side's £100million valuation on a player they bought from Manchester City for £10m in 2017.
Dortmund set August 10 – the day they travelled to their pre-season training camp – as the deadline for a deal to be agreed but they are now ensconced in Bad Regaz in Switzerland with nothing in place.
That prompted Zorc to confidently announce Sancho would not be going anywhere.
"We plan on having Jadon Sancho in our team this season, the decision is final. I think that answers all our questions," he told a press conference.
Negotiations appear to have been made more difficult by Zorc's revelation the 20-year-old's contract has three years left to run and not two as originally thought.
"Last summer we adjusted the salary to the performance development of Jadon. In this context, we have extended the contract until 2023," he added.
Last week United boss Ole Gunnar Solskjaer admitted signing Sancho presented a significant challenge but refused to be drawn on their pursuit.
Asked how difficult, he said: "Well, we're looking into all transfers differently. I'm not going to speak about individuals that are not our players."