Concise Construction of the ACDE Ring System of Calyciphylline A Type Alkaloids by a [5+2] Cycloaddition |
| |
Authors: | Dr Hugh Nakamura Manami Kawakami Dr Chihiro Tsukano Prof Dr Yoshiji Takemoto |
| |
Institution: | Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto, 606-8501 Japan |
| |
Abstract: | A concise route for construction of the ACDE ring skeleton in calyciphylline A type alkaloids was developed using an intramolecular 5+2] cycloaddition reaction of an oxidopyrylium species bearing a tetrasubstituted olefin. Key to the success of this reaction was the combination of acid and base, which accelerated the construction of this skeleton containing a spiro ring and vicinal quaternary carbon centers. The resultant tricyclic ADE ring compound was converted to an ACDE ring model through C−H oxidation and an aza-Wittig reaction. |
| |
Keywords: | [5+2] cycloaddition calyciphylline A daphniphyllum alkaloids daphniyunnine synthetic strategy |
|