Polyketo-enols and chelates. Part IV. The by-product in the xanthophanic–glaucophanic enol reaction: 2-acetyl-4,7-alkoxycarbonyl-1,6-dimethylnaphthalane

Abstract

The by-product described in the title is shown to be 2-acetyl-4,7-diethoxycarbonyl-1,6-dimethylnaphthalene by hydrolysis and decarboxylation to 2-acetyl-1,6-dimethylnaphthalene. Since the 1,6-relationship of the methyls is known the acetyl was degraded to a methyl group via a haloform reaction, metal hydride reduction, and hydrogenolysis. The product was shown to be 1,2,6-trimethylnaphthalene by side-chain tribromination to give 1,2,6-tribromomethylnaphthalene, identical with an authentic specimen and different from 1,4,6-tribromomethyl-naphthalene. The origin of the naphthalene is considered.