Enantioselective hydrosilylation of ketimines catalyzed by Lewis basic C2-symmetric chiral tetraamide

l-Proline derived C2-symmetric chiral tetraamide 5b was found to behave as an effective Lewis basic catalyst in the enantioselective hydrosilylation of ketimines, affording high isolated yields (up to 95%) and moderate to high enantioselectivities (up to 86% ee) for a broad range of ketimines. A clear synergistic effect of the two identical diamide units of 5b was observed for asymmetric induction.

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N,N′-Di-(N-formyl-l-prolyl)-hydrazineC12H18N4O4Ee = 100%[α]D20=-137.04 (c 0.108, EtOH)

N,N′-Di-(N-formyl-l-prolyl)-ethane-1,2-diamineC14H22N4O4Ee = 100%[α]D20=-81.25 (c 0.16, EtOH)

N,N′-Di-(N-formyl-l-prolyl)-propane-1,3-diamineC15H24N4O4Ee = 100%[α]D20=-89.04 (c 0.132, EtOH)

N,N′-Di-(N-formyl-l-prolyl)-butane-1,4-diamineC16H24N4O4Ee = 100%[α]D20=-111.03 (c 0.136, EtOH)

N,N′-Di-(N-formyl-l-prolyl)-(1S,2S)-1,2-diphenylethane-1,2-diamineC26H30N4O4Ee = 100%[α]D20=-61.54 (c 0.104, MeOH)

N,N′-Di-(N-formyl-l-prolyl)-(1R,2R)-1,2-diphenylethane-1,2-diamineC26H30N4O4Ee = 100%[α]D20=-127.88 (c 0.104, MeOH)

N,N′-Di-(N-methylformyl-l-valinyl)-ethane-1,2-diamineC16H30N4O4Ee = 100%[α]D20=-71.07 (c 0.242, CH3OH)

N,N′-Di-(N-formyl-l-piperidyl)-ethane-1,2-diamineC16H26N4O4Ee = 100%[α]D20=-114.4 (c 0.104, EtOH)

N,N′-Di-(N-formyl-l-prolyl)-benzene-1,2-diamineC18H22N4O4Ee = 100%[α]D20=-69.5 (c 0.154, EtOH)

N,N′-Di-(N-formyl-l-prolyl)-benzene-1,3-diamineC18H22N4O4Ee = 100%[α]D20=-160.0 (c 0.14, EtOH)

N,N′-Di-(N-formyl-l-prolyl)-benzene-1,4-diamineC18H22N4O4Ee = 100%[α]D20=-194.0 (c 0.1, EtOH)

N,N′-Di-(N-formyl-l-prolyl)-(1S,2S)-cyclohexane-1,2-diamineC18H28N4O4Ee = 100%[α]D20=-148.28 (c 0.160, EtOH)