6-(4-Methoxyphenyl)-5-methyl-2-(2-pyridinyl)-3,6-dihydro-2H-1,2-oxazine AIDS-138189 AIDS138189 Methyl 4-(5-methyl-2-(2-pyridinyl)-3,6-dihydro-2H-1,2-oxazin-6-yl)phenyl ether NSC644549