Asymmetric Counter-Anion-Directed Aminomethylation: Synthesis of Chiral β‑Amino Acids via Trapping of an Enol Intermediate
journal contributionposted on 09.01.2019, 00:00 by Zhenghui Kang, Yongheng Wang, Dan Zhang, Ruibo Wu, Xinfang Xu, Wenhao Hu
A novel enantioselective aminomethylation reaction of diazo compound, alcohol and α-aminomethyl ether enabled by asymmetric counteranion-directed catalysis is disclosed that offers an efficient and convenient access to furnish optically active α-hydroxyl-β-amino acids in high yield with high to excellent enantioselectivities. Control experiments and DFT calculations indicate that the transformation proceeds through trapping the in situ generated enol intermediate with methylene iminium ion, and the asymmetric induction was enabled by chiral pentacarboxycyclopentadiene anion via H-bonding and electrostatic interaction.
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enantioselectivitieAsymmetric Counter-Anion-Directed Aminomethylationcontrol experimentsTrappingchiral pentacarboxycyclopentadiene anioncounteranion-directed catalysisaccessα- hydroxyl -β-amino acidsdiazo compoundSynthesinovel enantioselective aminomethylation reactionDFT calculationsChiralEnol Intermediateinteractionmethylene iminium ioninductionenolα- aminomethyl ethertransformation proceedsAcid