Stable sulfur ylides. VIII. The reactions of 1,3-oxazin-4-one derivatives.

Abstract

6-Methyl-5-methylthio-2-[2(1H)-quinolylidene] methyl-1, 3-oxazin-4-one (1) was treated with acid to give 4-methyl-5-methylthio-3-[2(1H)-quinolylidene] pyridine-2, 6 (1H, 3H)-dione (2) in good yield. Similarly, 2-aminopyridine derivatives (7a-e) were obtained by the reaction of 1 with various amines. On the thermolysis of 1, 3-methylthio-2-[2 (1H)-quinolylidene]-3, 5-dioxohexanitrile (12) was obtained. When 1 was treated with trifluoroacetic anhydride, a trifluoroacetyl group was introduced at the active methine moiety of 1. No ring conversion occurred in the reaction of 6-methyl-5-methylthio-2-[2 (1H)-quinolylidene-2-quinolyl] methyl-1, 3-oxazin-4-one (13) with various reagents, whereas ring cleavage of the 1, 3-oxazine ring of 13 was observed. Dimethylsulfonium acetyl-N-phenylcarbamoylmethylide (18) was treated with quinoline 1-oxide and acetyl chloride to give 4-methyl-3-methylthio-1-phenyl-5-[2 (1H)-quinolylidene] pyridine-2, 6 (1H, 5H)-dione (20) instead of the 1, 3-oxazin-4-one derivative (19).