Chemical Correlation Experiments Research Articles

Boomerang‐Type Substitution Reaction: Reactivity of Fullerene Epoxides and a Halofullerenol

The C(s)-symmetric fullerene chlorohydrin C60(Cl)(OH)(OOtBu)4 reacts with 4-dimethylaminopyridine (DMAP) and 1,4-diazabicyclo[2.2.2]octane (DABCO) to yield two isomers with the formula C60(O)(OOtBu)4 in good yields. These isomers differ with respect to the location of the epoxy functionality. The one from DMAP is C(s) symmetric, whereas that from DABCO is C1 symmetric with the epoxy group on the central pentagon. Two different mechanisms are proposed to explain the chemoselectivity of these reactions. The reaction with DMAP involves single-electron transfer as the key step; DMAP acts as the electron donor. A combination of an oxygen-atom shift and S(N)2'' processes (boomerang substitution) are responsible for the formation of isomer with DACBO. Various related reactions support the proposed mechanisms. The structures of new fullerene derivatives were determined by spectroscopy, single-crystal X-ray analysis, and chemical correlation experiments.

Formation and isolation of simple, stable, acyclic di- and tripeptide hemiacetals

Di- and tripeptide aldehydes were found to undergo reaction with methanol to afford the corresponding methyl hemiacetals. These compounds, which possessed unusual stability, were isolated and characterized using NMR techniques and a chemical correlation experiment.