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Updated: Jul 13, 2026

Modification and Functionalization of the Guanidine Group by Tailor-made Precursors
Published on: April 27, 2017
Organocatalytic asymmetric nitroaldol reaction: cooperative effects of guanidine and thiourea functional groups
Yoshihiro Sohtome1, Nobuko Takemura, Keisuke Takada
1Graduate School of Pharmaceutical Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Abstract:
Catalytic enantio- and diastereoselective nitroaldol reactions were explored by using designed guanidine-thiourea bifunctional organocatalysts under mild and operationally simple biphasic conditions. These catalytic asymmetric reactions have a broad substrate generality with respect to the variety of aldehydes and nitroalkanes. Based on this catalytic nitroaldol process, straightforward syntheses of cytoxazone and 4-epi-cytoxazone were achieved. These catalytic nitroaldol reactions require KI as an additive for highly asymmetric induction; it operates by inhibiting the retro mode of the reaction. On the basis of studies of structure and catalytic-activity relationships, a plausible guanidine-thiourea cooperative mechanism and a transition state of the catalytic reactions are proposed. Drastic substituent effects on the catalytic properties of this catalyst may lead to the development of new chiral surfactants.
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