Lactones 39.1 Chemical and microbial synthesis of lactones from (−)-α- and (+)-β-thujone

The effective method of isolation, separation and purification of (−)-α- and (+)-β-thujone (1a and 1b) from Thuja occidentalis was elaborated. Chemical (m-CPBA) and microbial Baeyer-Villiger oxidation of (−)-α- and (+)-β-thujone was carried out. Four new bicyclic δ-lactones (2a, 2b, 3a and 3b) with condensed cyclopropane ring were obtained.

The four new bicyclic δ-lactones with condensed cyclopropane ring were obtained from α- and β-thujone. Both isomers of thujone were isolated from white cedar leaves oil (Thuja occidentalis).Highlights► The monoterpenoid ketones: α- and β-thujone were isolated from Thuja occidentalis essential oil. ► Chemical and microbial oxidation of α- and β-thujone afforded four new δ-lactones with condensed cyclopropane ring. ► The crystal structures of three new lactones are reported.