KETEN .V. REACTION OF DIMETHYLKETEN WITH HETEROAROMATIC N-OXIDES

Phenanthridine N-oxide forms an adduct with two molecules of dimethylketen, which has been shown to be a phenanthridino[5,6-b] [1,2]oxazepinedione (I). Isoquinoline N-oxide forms a similar adduct (VI). The reaction of phenanthridine N-oxide with dimethylketen in various solvents also produces phenanthridine and phenanthridone. Isoquinoline N-oxide reacts with dimethylketen in methanolic solution to form isoquinoline, 1-(1-methoxy-carbonyl-1-methylethyl)-1,2-dihydro- 2-isobutyrylisoquinoline (XVIII), and 2-methoxyisobutyric acid, the last compound indicating that deoxygenation occurs by formation of an α-lactone.