2-Methoxy-5,6,6-trimethyl-5,6-dihydro-1,4,3-oxathiazine 4,4-dioxide 36743-52-9 AIDS-127659 AIDS127659 Methyl 5,6,6-trimethyl-4,4-dioxido-5,6-dihydro-1,4,3-oxathiazin-2-yl ether NSC174530