Organoaluminum Compounds as Catalysts for Monohydroboration of Carbodiimides

Abstract

he effectivecatalytic activity of organoaluminumcompoundsfor the monohydroboration of carbodiimideshas beendemonstrated. Twoaluminumcomplexes,2and3,weresynthesizedandcharacterized.Theefficientcatalyticperformances of fouraluminum hydridecomplexes 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), andL4AlH(NMe3)(L4=o-C6H4(N-Dipp)(CH=N-Dipp),Dipp=2,6-iPr2C6H3;4), andan aluminum alkylcomplex L1AlMe2(5)wereusedfor the monohydroboration of carbodiimidesin-vestigatedundersolvent-free andmildconditions. Com-pounds1–3and5can produce monohydroboratedN-boryl-formamidine, whereas4can affordtheC-borylformamidineproduct. Asuggested mechanismof this reactionwas ex-plored, andthe aluminumformamidinate compound6wascharacterized by single-crystal X-ray,also astoichiometricre-actionwas investigated.