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Synthetic Studies on Camptothecins. Part 1 |
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| Authors: | Li‐Peng Zhang Yong Bao Yun‐Yan Kuang Fen‐Er Chen |
| Affiliation: | 1. Department of Chemistry, Fudan University, Shanghai, 200433, P.?R. China;2. Institute of Biomedical Science, Fudan University, Shanghai, 200032, P.?R. China, (phone/fax: +86‐21‐65643811) |
| Abstract: | A six‐step asymmetric total synthesis of (20S)‐camptothecin ( 1 ) has been accomplished in 25% overall yield starting from the known pyridone 3 . The key steps in this synthesis are the chemoselective Ni‐catalyzed hydrogenation of 3‐cyanopyridone 6 to 3‐formylpyridone 7 in AcOH/pyridine/H2O and the Davis asymmetric hydroxylation of tricyclic lactone 4 utilizing a chiral N‐sulfonyloxaziridine into (4′S)‐tricyclic hydroxylactone 2 . |
| Keywords: | Camptothecin Hydroxylation, asymmetric Davis reagent Friedlä nder condensation |