Preparation and identification of bis(formylmethano)[60]-fullerene isomers: the first systematic study on bifunctionalized [60]fullerenes with dissymmetric addends

摘要

Fourteen isomers of bis(formylmethano)C_(60) were isolated and characterized.A mixture of the bisadducts was obtained by the reaction of C_(60) with an alpha-formylsulfonium ylide,and then separated into 15 fractions by preparative HPLC,preparative TLC,and recycling preparative HPLC.Fourteen of the fifteen fractions were found to consist of a single isomer,respectively,which were assigned to the trans-2 (3 diastereo-isomers),trans-3 (3 diastereo-isomers),trans-4 (3 diastereo-isomers),equatorial (2 diastereo-isomers),and cis-2 (3 diastereo-isomers) bisadducts by the comparison of their UV/vis spectra with those of the bisadducts obtained by the Bingel-Hirsch reaction.The ~1H and ~(13)C NMR analysis,the transformation of the formyl groups,and the dipole moment calculation clarified the stereochemistry of the substituents on the two cyclopropane bridge-head carbons (in/in,in/out,and out/out).