A study towards the regioselective synthesis of the e,e,e trisadduct of C60 via the [4+2] Diels-Alder reaction with tethers bearing orthoquinodimethane precursors

Abstract

The regioselective synthesis of an e,e,e trisadduct of C60 via the Diels-Alder reaction with orthoquinodimethanes has been attempted employing the tether-directed remote functionalization approach. Opened-structure tether 10 and macrocyclic tethers 16 and 21 were synthesized for this purpose. The functionalization of C60 afforded inseparable mixtures of regiomeric trisadducts and the regioselective formation of the e,e,e trisadduct was not feasible even when the more preorganized tethers 16 and 21 were employed. The in situ thermal generation of orthoquinodimethanes from the 1,2-bis(bromomethyl)benzene precursors requires high temperatures and is followed by fast, irreversible cycloaddition with C60 to afford thermally stable products, which prevents the achievement of high regioselectivities. © ARKAT-USA, Inc.