Regio- and diastereoselective synthesis of bis- and tetrakisadducts of C-70 by directed remote functionalization using troger base tethers

Abstract

Double Bingel cyclopropanation of C70 with bismalonates featuring Tröger base derivatives as chiral spacers afforded bisadducts with almost perfect regio- and stereoselectivity. The excellent directing property of these rigidly folded spacers in the remote functionalization of the higher fullerene was further highlighted by the selective formation of a product with a novel bisaddition pattern involving the C(7)-C(22) and C(33)-C(34) bonds of C70. Enantiomerically pure bisadducts of C70 were prepared by highly diastereoselective transformations of bismalonates incorporating optically pure Tröger base tethers. The absolute configuration of these bisadducts was established by comparison of circ..