UBS Securities Canada, Inc. v. Sands Brothers Canada, Ltd., 2009 ONCA 328 provides a nice summary of when specific performance is available:
There is no dispute about the applicable legal principles. When fashioning a remedy for a breach of contract, the object is to place the injured party in the position that he or she would have been had the contract been performed. Typically, damages are ordered. However, where damages are inadequate to compensate an injured party for its losses, specific performance may be ordered. Accordingly, specific performance may be ordered where the subject matter of a bargain is unique or irreplaceable because, in those circumstances, damages may be inadequate. The remedy for an anticipatory breach of contract is discretionary. The exercise of discretion requires an assessment of the parties’ conduct and the factual context.