Formal Total Synthesis of (−)‐Taxol through Pd‐Catalyzed Eight‐Membered Carbocyclic Ring Formation |
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| Authors: | Sho Hirai Masayuki Utsugi Mitsuhiro Iwamoto Prof. Dr. Masahisa Nakada |
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| Affiliation: | Department of Chemistry and Biochemistry, School of Advanced Science and Engineering, Waseda University, 3‐4‐1 Ohkubo, Shinjuku‐ku, Tokyo 169‐8555 (Japan), Fax: (+81)?3‐5286‐3240 |
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| Abstract: | A formal total synthesis of (?)‐taxol by a convergent approach utilizing Pd‐catalyzed intramolecular alkenylation is described. Formation of the eight‐membered carbocyclic ring has been a problem in the convergent total synthesis of taxol but it was solved by the Pd‐catalyzed intramolecular alkenylation of a methyl ketone affording the cyclized product in excellent yield (97 %), indicating the high efficiency of the Pd‐catalyzed intramolecular alkenylation. Rearrangement of the epoxy benzyl ether through a 1,5‐hydride shift, generating the C3 stereogenic center and subsequently forming the C1–C2 benzylidene, was discovered and utilized in the preparation of a substrate for the Pd‐catalyzed reaction. |
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| Keywords: | cyclization enantioselectivity natural products palladium total synthesis |
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