Investigation of boron-fluorine bond reactivity in meso-aryl-substituted BODIPYs towards carborane O-nucleophiles.

Abstract

In this work meso-aryl-substituted BODIPYs (Ar = Ph, p-Br-C₆H₄, C₆F₅) were used as starting compounds for modification of their boron atoms with carborane O-nucleophiles to afford novel boron-substituted carborane BODIPY derivatives. This type of reactions has not been used previously to prepare carborane structures. The reactions proceeded via the cleavage of boron-fluorine bonds in BODIPYs under the action of AlCl₃ followed by the treatment with carborane O-nucleophiles such as 1-hydroxymethyl-o-carborane or 1,2-dihydroxymethyl-o-carborane. While reactions of meso-aryl-substituted BODIPYs with 1-hydroxymethyl-o-carborane proceeded selectively, forming mono- or dicarborane-substituted BODIPYs, the reactions of 1,2-bis(hydroxymethyl)-o-carborane were not selective yielding a mixture of products. The structures of novel compounds were confirmed by ¹H and ¹¹B NMR and mass spectrometry. The structures of some prepared carborane BODIPY compounds were further supported by their single X-ray crystal structures.