Synthetic studies on optically active furofuran and diarylbutane lignans^*

* This review was written in response to the author’s receipt of the JSBBA Award for Young Scientists in 2017.

Abstract

Lignans are a large class of naturally occurring secondary metabolites which are widely spread within the plant kingdom. Their diverse structures and variety of biological activities have fascinated organic chemists. For synthesizing optically active lignans, we have developed the novel asymmetric dimerization of cinnamic acid derivatives, and applied it to the enantioselective syntheses of furofuran lignans (yangambin, sesamin, eudesmin, caruilignan A) and diarylbutane lignans (sauriols A and B). This review summarizes the methodology of our asymmetric dimerization of cinnamic acid derivatives, and efficient total syntheses of furofuran and diarylbutane lignans reported by our and other groups.

Optically active furofuran and diarylbutane lignans were synthesized in short steps employing the asymmetric dimerization of cinnamic acid derivatives.

Keywords:

• Synthesis
• oxidative dimerization
• electrochemical oxidation
• furofuran lignan
• diarylbutane lignan

Acknowledgments

I am deeply grateful to Professor Hidenori Watanabe (The University of Tokyo), Emeritus Professor Kenji Mori (The University of Tokyo), Emeritus Professor Takeshi Kitahara (The University of Tokyo), Professor Ken Ishigami (Tokyo University of Agriculture) for their continuous encouragement and valuable discussion. I also thank Dr. Akiko Furuta for the electrochemical oxidation of cinnamic acid derivatives.

Notes

* This review was written in response to the author’s receipt of the JSBBA Award for Young Scientists in 2017.