Formation of C6 C2 -Enol Ethers in the Acid-Catalyzed Hydrolysis of Erythro-Veratrylglycerol-β-(2-Methoxyphenyl) Ether

Acid-catalyzed hydrolysis of erythro-veratrylglycerol-β-(2-methoxyphenyl) ether in mixed aqueous-organic media yields, in addition to Hibbert's ketones formed via readily hydrolyzable C 6 C 3 -enol ether intermediates, the cis-and trans-isomers of a C 6 C 2 -enol ether. The formation of these C 6 C 2 isomers involves the elimination of the γ-carbinol group as formaldehyde. Both C 6 C 2 -enol ether isomers are unexpectedly resistant towards hydrolysis. In aqueous dioxane and ethanol systems, the competing formation of the C 6 C 2 -enol ethers is increased with increasing concentration of the organic solvent and with increasing reaction temperature.