Evaluating dynamic kinetic resolution strategies in the asymmetric hydrosilylation of cyclic ketimines

Attempts at performing dynamic kinetic resolution on a series of cyclic ketimines by making use of an asymmetric organocatalysed hydrosilylation gave modest conversion and moderate to good enantioselectivities. In the case of α-tetralone derivatives, the use of an N-benzyl protecting group was found to be crucial in obtaining enhanced levels of selectivity.

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N-[(1R,2S)-2-Methylcyclohexyl]-benzenemethanamineC14H21Nee = 77%[α]D25=-3.6 (c 1.1 EtOH)Source of chirality: Asymmetric synthesisAbsolute configuration: (1R,2S)

(1R,2S)-1-Amino-2-methylcyclohexane hydrochlorideC7H16ClNee = 77%[α]D20=+3.6 (c 0.65, EtOH)Source of chirality: Asymmetric synthesisAbsolute configuration: (1R,2S)

(1S,2S)-N-Benzyl-1-amino-2-methyl-1,2,3,4-tetrahydronaphthaleneC18H21Nee = 61%[α]D20=-17.0 (c 0.4, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (1S,2S)

(S)-N-Benzyl-1,2,3,4-tetrahydronaphthalen-1-amineC17H19Nee = 55%[α]D20=-6.0 (c 0.66, CHCl3)Source of chirality: Asymmetric synthesisAbsolute configuration: (S)