Efficient syntheses of some 1-naphthylalkyl ketones and studies on their autooxidation in basic medium

Birch reductions of 4,6-dimethoxy-1-naphthylalkyl ketones 1 provided in fair to good yields the demethoxylated products, 6-methoxy-1-naphthylalkyl ketones 2(a–g), not easily accessible by other procedures. Autooxidation of these ketones in basic medium afforded the diketones 6(a–c), the acid 2h, and interestingly the phenol 5. Extension of this reduction to the related tricyclic ketone 8 afforded 9a, the phenolic ketone 9b; and significantly the dihydrocoumarin derivative 10 as a result of autooxidation of 9a. The mechanisms for demethoxylation and autooxidation have been discussed.