Toast coconut in a small heavy skillet over medium heat, stirring frequently, until golden-brown, about 5 minutes. Cut pineapple crosswise into 8 slices (about 3/4 inch thick) and core slices. Stir together remaining ingredients in a shallow glass baking dish and add pineapple in 1 layer, turning to coat evenly. Marinate, turning occasionally, 30 minutes. Prepare a gas grill for direct-heat cooking over medium-high heat; see Grilling Procedure . Oil grill rack. Grill pineapple (reserve marinade), covered, turning once, until grill marks appear and pineapple is heated through, about 4 minutes. Serve pineapple with marinade and sprinkle with toasted coconut.