Synthesis and crystal structures of guanidinatoaluminum complexes and catalytic study for MPV reduction

Treatment of a secondary amine (piperidine or N -benzylmethylamine) with sequentially trimethylaluminum and carbodiimide CyN C NCy in a molar ratio of 1:1:1 afforded two mononuclear guanidinatoaluminum complexes, [{(C 5 H 10 N)C(NCy) 2 }AlMe 2 ] ( 1 ) and. [{(Bz(Me)N)C(NCy) 2 }AlMe 2 ] ( 2 ). Introducing dry oxygen slowly into the solution of 1 or 2 , [{(C 5 H 10 N)C(NCy) 2 }AlMe( μ -OMe)] 2 ( 3 ) and [{(Bz(Me)N)C(NCy) 2 }AlMe( μ -OMe)] 2 ( 4 ) were obtained, respectively. Both of 3 and 4 were also prepared by treatment of piperidine or N-benzylmethylamine with trimethylaluminum and carbodiimide CyN C NCy in the presence of O 2 . The complexes 1 – 4 were characterized by 1 H, 13 C NMR spectra and single crystal X-ray diffraction analysis. 1 – 4 were also used to catalyze the Meerwein–Ponndorf–Verley (MPV) reaction.