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Enantioselective Synthesis of Both Epimers at C-21 in the Proposed Structure of Cytotoxic Macrolide Callyspongiolide.

ABSTRACT: Both epimers at C-21 in the proposed structure of (+)-callyspongiolide have been synthesized in a convergent and enantioselective manner. The 14-membered macrolide with a sensitive C2-C3 cis-olefin functionality was installed by a Yamaguchi macrolactonization of hydroxyl alkynoic acid followed by hydrogenation over Lindlar's catalyst. The C5 methyl stereocenter was constructed by a ring-closing olefin metathesis followed by addition of methyl cuprate to an ?,?-unsaturated ?-lactone. Other key reactions are chiral Corey-Bakshi-Shibata (CBS) reduction and Sonogashira coupling to conjoin the macrocyclic core and side chain.

SUBMITTER: Ghosh AK

PROVIDER: S-EPMC6037179 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

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Enantioselective Synthesis of Both Epimers at C-21 in the Proposed Structure of Cytotoxic Macrolide Callyspongiolide.

Ghosh Arun K AK Kassekert Luke A LA

Organic letters 20160622 13

Both epimers at C-21 in the proposed structure of (+)-callyspongiolide have been synthesized in a convergent and enantioselective manner. The 14-membered macrolide with a sensitive C2-C3 cis-olefin functionality was installed by a Yamaguchi macrolactonization of hydroxyl alkynoic acid followed by hydrogenation over Lindlar's catalyst. The C5 methyl stereocenter was constructed by a ring-closing olefin metathesis followed by addition of methyl cuprate to an α,β-unsaturated δ-lactone. Other key re ...[more]

PMID: 27331421

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