Total Synthesis of (+)‐Gracilamine Based on an Oxidative Phenolic Coupling Reaction and Determination of Its Absolute Configuration |
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| Authors: | Dr. Minami Odagi Yoshiharu Yamamoto Prof. Dr. Kazuo Nagasawa |
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| Affiliation: | Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, TUAT, Koganei city, Tokyo, Japan |
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| Abstract: | The enantioselective total synthesis of (+)‐gracilamine ( 1 ) is described. The strategy features a diastereoselective phenolic coupling reaction followed by a regioselective intramolecular aza‐Michael reaction to construct the ABCE ring system. The configuration at C3a in 1 was controlled by the stereocenter at C9a, which was selectively generated (91 % ee) by an organocatalytic enantioselective aza‐Friedel–Crafts reaction developed by our research group. This synthesis revealed that the absolute configuration of (+)‐gracilamine is 3aR, 4S, 5S, 6R, 7aS, 8R, 9aS. |
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| Keywords: | aza-Friedel– Crafts reaction natural products organocatalysis oxidative phenolic coupling total synthesis |
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