Preferential production of microalgal hydrocarbon pentathiolates by the photoinitiated thiol-ene reaction of botryococcene

Abstract

To expand the applications of algal biomass materials, the reactivity of a microalgal hydrocarbon oil, botryococcene (E)-2,3,7,10,13,16,20,21-octamethyl-6,17-dimethylene-10-vinyldocosa-1,11,21-triene), was explored. Botryococcene was reacted with an excess of several alkylthiols in the presence of a photoradical initiator under UV irradiation (λ = 365 nm). In all cases, the thiol-ene reaction proceeded at the four vinylidenes positioned at C2, C6, C17, and C21 and at the C10 vinyl moiety, but the sterically hindered C11–C12 vinylene was inactive. Thus, pentathiolated botryococcenes were preferentially produced and isolated in good yields.