Homogeneous Lewis and Brønsted acids as catalysts for β-pinene oxide rearrangement to prepare myrtenol and myrtanal

Abstract

Myrtenol and myrtanal find their utilization as fine chemicals or intermediates for the synthesis of food additive myrtanol. β-Pinene oxide rearrangement was studied using homogeneous Lewis and Brønsted acids as catalysts for the production of these compounds. The composition of reaction products depended on the type of active sites. Lewis active sites favoured the formation of myrtanal while in presence of Brønsted active sites undesirable perillyl aldehyde and perillyl alcohol were formed to a high extent. Optimal reaction conditions for myrtenol and myrtanal preparation were found. With 5 mol.% of anhydrous SnCl2 as Lewis acid catalysts and 1,4-dioxane as the solvent β-pinene oxide achieved total conversion with 95% selectivity to desired products.