Highly enantioselective addition of dimethylzinc to arylaldehydes catalyzed by (2S)-1-ferrocenyl-methylaziridin-2-yl(diphenyl)methanol

Asymmetric addition of dimethylzinc to a wide variety of aromatic aldehydes is described in the presence of a catalytic amount of chiral β-amino alcohol [(2S)-1-ferrocenyl- methylaziridin-2-yl(diphenyl)methanol], and a reaction enantioselectivity of up to 97.5% ee was achieved in this transformation in the absence of additional metals such as Ti or Ni. The results showed that this particular addition reaction, characterized by the lower reactivity of dimethylzinc with aldehydes, was more sensitive to structural variations in substrate aldehydes than the corresponding diethylzinc addition. A possible transition state for the catalytic asymmetric addition has been proposed on the basis of previous studies.

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(S)-1-m-Phenoxyphenyl-1-ethanolC14H14O2[α]D20=-28.0 (c 0.26, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (S)

(S)-1-[3,4-(Methylenedioxy)phenyl]-1-ethanolC9H10O3[α]D20=-42.0 (c 0.61, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (S)

(S)-1-p-Dimethylaminophenyl-1-ethanolC10H15NO[α]D20=-8.9 (c 0.10, CHCl3)Source of chirality: asymmetric synthesisAbsolute configuration: (S)