Pyrimidine ortho-quinodimethanes. Part 2: Synthesis of new [60]fullerene adducts based on substituted pyrimidine derivatives and their 1H NMR dynamic study

The Diels–Alder reaction of various pyrimidine ortho-quinodimethanes generated in situ with C₆₀ gives access to a variety of new fullerodihydroquinazoline derivatives. This variety is increased since substituents on the pyrimidine ring can be easily modified before or after its reaction with C₆₀. Variable temperature ¹H NMR spectra provided thermodynamic parameters related to the boat-to-boat interconversion of the cyclohexene ring fused to the fullerene moiety. The mass spectra of the prepared cycloadducts show that the retro-Diels–Alder process takes place easily with elimination of the corresponding diene molecule.