Development of Novel Hydrogen-Bond Donor Catalysts

This work describes novel, effective hydrogen-bond (HB) donor catalysts based on a known bifunctional tertiary amine-thiourea, a privileged structure, which has been proven to be one of the most widely used organocatalysts. These HB donor catalysts derived from quinazoline and benzothiadiazine were initially synthesized as novel HB donors with their HB-donating abilities being measured by analytical methods. They were found to be effective for a variety of asymmetric transformations including Michael reactions of a, b-unsaturated imides and hydrazination reactions of 1,3-dicarbonyl compounds. Thiourea catalysts that have an additional functional group are also described. Specifically, thioureas that bear a hydroxyl group were synthesized and subsequently used as novel bifunctional organocatalysts for catalytic, asymmetric Petasis-type reactions involving organoboronic acids as nucleophiles. These addition reactions were difficult to achieve using existing organocatalysts. One of the developed catalytic methods can be applied to the synthesis of biologically interesting peptide-derived compounds possessing unnatural vinyl glycine moieties. These findings introduce new criteria required for the development of organocatalysts for asymmetric reactions, thus making a significant contribution to the field of organocatalysis.

Auteur

Dr. Tsubasa Inokuma,
The Scripps Research Institute

Tsubasa Inokuma was born in Okayama in 1983. He studied chemistry at Kyoto University and obtained BSc (2005) and MSc (2007) degree at Kyoto University under the guidance of Prof. Yoshiji Takemoto. In 2008, during his PhD course, he became an assistant professor at Kyoto University. He obtained PhD degree at Kyoto University in 2011 under the supervision of Prof. Yoshiji Takemoto. Since 2012, he has been working as a postdoctoral fellow in Barbas laboratory at The Scripps Research Institute. His research interests are development of novel catalytic reaction and bioconjugation methods.

Contenu
Introduction.- Development of HB donor catalysts.- Development and properties of novel HB donor catalysts.- Asymmetric Michael addition to alpha,beta-unsaturated imides catalyzed by HB donors.- Asymmetric Hydrazination of activated methylene compounds catalyzed by HB donors.- Development of hydroxy thiourea catalysts.- Asymmetric Michael addition of gamma-hydroxyenones and alkenylboronic acids.- Asymmetric Petasis Reaction of N-aryl-alpha-iminoamides and Alkenylboronates.- Conclusion.