1,4-Dimethyl-9H-indeno[1,2-d][1,2]oxathiin-9-one 3,3-dioxide 55039-39-9 AIDS-127489 AIDS127489 NSC166739 {9H-Indeno[1,2-d][1,2]oxathiin-9-one,} 1,4-dimethyl-, 3,3-dioxide