Organoaluminum Compounds as Catalysts for Monohydroboration of Carbodiimides

Abstract

Abstract 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 L1AlH2 (L1=HC(CMeNAr)2, Ar=2,6‐Et2C6H3; 1), L2AlH2(NMe3) (L2=o‐C6H4F(CH=N‐Ar), Ar=2,6‐Et2C6H3; 2), L3AlH (L3=2,6‐bis(1‐methylethyl)‐N‐(2‐pyridinylmethylene)phenylamine; 3), and L4AlH(NMe3) (L4=o‐C6H4(N‐Dipp)(CH=N‐Dipp), Dipp=2,6‐iPr2C6H3; 4), and an aluminum alkyl complex L1AlMe2 (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.