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Updated: Jun 4, 2026

Preparation of Contiguous Bisaziridines for Regioselective Ring-Opening Reactions
Published on: July 28, 2022
Cooperative Chiral Induction in Aromatic N,N'-Dialkylated Urea Organocatalyst Enables Asymmetric Aza-Henry Reaction
Fumi Takeda1, Mayumi Kudo2, Mamika Ogura1
1Department of Chemistry, Faculty of Science, Ochanomizu University, 2-1-1 Otsuka, Bunkyo-ku, Tokyo 112-8610, Japan.
Abstract:
N,N'-Dialkylation of N,N'-diphenylurea induces a change from (trans, trans) to (cis, cis) conformation, enabling the construction of helical oligoureas with flexible aromatic multilayered structures that exhibit a dynamic equilibrium of axially chiral conformers. In this study, we utilized this property of folded aromatic N,N'-dialkylated ureas to develop an organocatalyst. We designed and synthesized compound 3 bearing thioureas on the phenyl rings as substrate recognition sites, together with a chiral N-substituent. We found experimentally and theoretically that the sodium ion interacts with the chiral N-ethylene glycol side chain to form a chiral cavity that enables asymmetric catalysis of the aza-Henry reaction of N-Boc-imine with nitromethane, affording up to 60% yield and 64% ee. The addition of the sodium cation was key to the catalytic reaction and did not affect the dynamic nature of the chirality of 3. The introduction of various substituents into such aromatic layered ureas is expected to provide a range of unique molecular recognition functions.
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