Rare-Earth-Metal-Catalyzed Kinetic Resolution of Chiral Aminoalkenes via Hydroamination: The Effect of the Silyl Substituent of the Binaphtholate Ligand on Resolution Efficiency.

The kinetic resolution of α-substituted aminopentenes via intramolecular hydroamination was investigated using various 3,3'-silyl-substituted binaphtholate yttrium catalysts. High efficiencies in the kinetic resolution were observed for methyl-, benzyl-, and phenyl-substituted substrates utilizing the cyclohexyldiphenylsilyl-substituted catalyst with resolution factors reaching as high as 90(5) for hex-5-en-2-amine (). Kinetic analysis of the enantioenriched substrates with the matching and mismatching catalyst revealed that the efficiency of catalyst benefits significantly from a favorable Curtin-Hammett pre-equilibrium and by a large ratio. Other binaphtholate catalysts were less efficient due to a less favorable Curtin-Hammett pre-equilibrium, which often favored the mismatching substrate-catalyst combination. Cyclization of the matched substrate proceeds generally with large -selectivity, whereas the -ratio for mismatched substrates is significantly diminished, favoring the -cyclization product isomer in some instances.