B(C6F5)3-Mediated Transformations and Hydrogenation of Carbodiimides

The reactivity of a series of carbodiimides RN=C=NR (R= tBu (1a), iPr (1b), SiMe3 (1c), and Dipp (2,6-di-iso-propylphenyl (1d)) with B(C6F5)(3) was investigated. After initial adduct formation, several distinct reaction pathways were identified. These pathways involve either isomerization of the carbodiimide to cyanamide derivatives or insertion of a carbodiimide into a B-C bond of B(C6F5)(3) to yield four-membered heterocycles. In the presence of dihydrogen, stepwise hydrogenation of the heteroallene moiety in the carbodiimides was achieved, which yielded the respective amidine-B(C6F5)(3) adducts and amidinium borate salts upon reaction with one or two equivalents of H-2, respectively.