A Dipyrrin Programmed for Covalent Loading with Fullerenes.

Abstract

We describe here a di‐(β,β′‐sulfoleno)pyrrin programmed for efficient and specific β,β′‐functionalization via [4+2] cycloaddition reactions. At 120 °C and in the presence of an excess of C60‐fullerene the di‐(β,β′‐sulfoleno)pyrrin decomposed cleanly, furnishing a di‐(β,β′‐fullereno)pyrrin and the corresponding monofullereno‐dipyrrin in an overall yield of 96 %. Hence, relatively mild thermolysis of the di‐(β,β′‐sulfoleno)pyrrin induced stepwise extrusion of two equivalents of SO2, producing highly reactive dipyrrin‐β,β′‐diene intermediates readily, providing a very effective path to [4+2]‐cycloadducts. As presented here by the example of the covalent attachment of C60‐fullerene units, a convenient general methodology for the efficient synthesis of covalent dipyrrin β,β′‐cycloadducts is made available.