Foxes boss Ian Holloway revealed he had been rebuffed in a bid, with Chelsea unwilling to send Sinclair to a team in Leicester's position.
Holloway admitted he had been hopeful of signing the 18-year-old, who spent a spell on loan at the manager's former club Queens Park Rangers earlier this season. "We have now been told we can't have him," said Holloway. "Chelsea do not want to let him go to a team that's where we are.
"There's one struck off that we had half-planned and half-promised."