In a small bowl, combine all ingredients (except chicken). Reserve ¾ cup for basting; cover and refrigerate. Pour the rest of the marinade in a large zip bag. Add the chicken to the bag, and refrigerate to let marinate overnight.
Drain the chicken; discard the marinade.
Grill the chicken, covered on indirect heat until done. Baste occasionally with the reserved marinade during the last 5 minutes.
Grill the pineapple slices, basted with butter and brown sugar too, if desired.