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

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.