Preheat oven to 375°F. Grease an 8- or 9-inch round baking pan; set aside. Unroll dough (do not separate); press perforations to seal. Brush dough with melted butter. In a small bowl, stir together the granulated sugar and cinnamon; sprinkle over dough. Starting from a long side, roll up dough. Using a sharp knife, slice dough into eight pieces. Arrange rolls, cut sides up, in prepared pan, flattening each slightly.