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Asymmetric Formal Synthesis of Azadirachtin |
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| Authors: | Dr. Naoki Mori Prof. Dr. Takeshi Kitahara Prof. Dr. Kenji Mori Prof. Dr. Hidenori Watanabe |
| Affiliation: | 1. Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1‐1‐1 Yayoi, Bunkyo‐ku, Tokyo 113‐8657 (Japan);2. Current address: Kitasato University, 5‐9‐1 Shirokane, Minato‐ku, Tokyo 108‐0193 (Japan);3. Present address: Photosensitive Materials Research Center, Toyo Gosei Co., Ltd, 4‐2‐1 Wakahagi, Inzai‐shi, Chiba 270‐1609 (Japan) |
| Abstract: | An asymmetric formal synthesis of azadirachtin, a potent insect antifeedant, was accomplished in 30 steps to Ley’s synthetic intermediate (longest linear sequence). The synthesis features: 1) rapid access to the optically active right‐hand segment starting from the known 5‐hydroxymethyl‐2‐cyclopentenone scaffold; 2) construction of the B and E rings by a key intramolecular tandem radical cyclization; 3) formation of the hemiacetal moiety in the C ring through the α‐oxidation of the six‐membered lactone followed by methanolysis. |
| Keywords: | acetals cyclizations natural products radicals stereoselectivity |