Combine the peaches, sugar, water, ½ cup bourbon, cinnamon stick, and peppercorns in a heavy saucepan. Bring the mixture to a rolling boil over high heat. Boil until the peaches can be pierced easily with a fork, but before they soften, about 5 minutes.
Remove the pan from the heat and let it cool to room temperature. Refrigerate the peaches in the syrup for at