Spirodienones. Part 2. The synthesis of some heterocyclic spirodienones by phenolic coupling

Abstract

The oxidation with active manganese dioxide of a series of 2,4′-dihydroxydiphenyl ethers to the corresponding p-benzoquinone monoacetals (1,3-benzodioxole-2-spirocyclohexadien-4′-ones) is described; among the dienones prepared were monoacetals of nitro-p-benzoquinone and of p-fluoranil. Attempted ether formation with 2,6-di-t-butyl-4-bromophenol and either 2- or 3-methoxyphenol failed, small quantities of unsymmetric biphenyls being formed in a novel arylation reaction. A spirobenzoxazole can be prepared by oxidation of a 2,4′-dihydroxydiphenylamine. Substituent effects in the hydrolysis of derived spirodienols have been observed.