Twofold cycloaddition of 2,4,6-trimethoxy-benzonitrile oxide to [60]fullerene

The 22 conceivable regioisomers of isoxazolo-fullerenes are listed, combine d with a proposed nomenclature for their addition patterns. Two of them (I* (mm2), I*(2/m)) are impossible on sterical hindrance. The twofold cycloaddi tion of 2,4,6-trimethoxy-benzonitrile oxide to [60]fullerene yields in a co mplex mixture of bisadducts 1. By combined HPLC separations, we isolated 11 fractions, which are distinguishable in their NMR spectra. From comparison of the possible symmetries for isoxazolo-fullerenes and from the spectra o f the isolated reaction products 1 can be concluded that some fractions con tain two bisadducts. In the end our analytical data corresponds to 16 bisad ducts of 20 possible ones. (C) 1999 Elsevier Science Ltd. All rights reserv ed.