Organoaluminum Compounds as Catalysts for Monohydroboration of Carbodiimides

The effective catalytic activity of organoaluminum compounds for the monohydroboration of carbodiimides has been demonstrated. Two aluminum complexes, 2 and 3, were synthesized and characterized. The efficient catalytic performances of four aluminum hydride complexes L¹ AlH₂ (L¹ =HC(CMeNAr)₂ , Ar=2,6-Et₂ C₆ H₃ ; 1), L² AlH₂ (NMe₃ ) (L² =o-C₆ H₄ F(CH=N-Ar), Ar=2,6-Et₂ C₆ H₃ ; 2), L³ AlH (L³ =2,6-bis(1-methylethyl)-N-(2-pyridinylmethylene)phenylamine; 3), and L⁴ AlH(NMe₃ ) (L⁴ =o-C₆ H₄ (N-Dipp)(CH=N-Dipp), Dipp=2,6-iPr₂ C₆ H₃ ; 4), and an aluminum alkyl complex L¹ AlMe₂ (5) were used for the monohydroboration of carbodiimides investigated under solvent-free and mild conditions. Compounds 1-3 and 5 can produce monohydroborated N-borylformamidine, whereas 4 can afford the C-borylformamidine product. A suggested mechanism of this reaction was explored, and the aluminum formamidinate compound 6 was characterized by single-crystal X-ray, also a stoichiometric reaction was investigated.