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Magnesiate Addition/Ring-Expansion Strategy To Access the 6-7-6 Tricyclic Core of Hetisine-Type C20-Diterpenoid Alkaloids.

ABSTRACT: A synthetic strategy to access the fused 6-7-6 tricyclic core of hetisine-type C20-diterpenoid alkaloids is reported. This strategy employs a Diels-Alder cycloaddition to assemble a fused bicyclic anhydride intermediate, which is elaborated to a vinyl lactone-acetal bearing an aromatic ring in five steps. Aromatic iodination is followed by magnesium-halogen exchange with a trialkyl magnesiate species, which undergoes intramolecular cyclization. Subsequent oxidation provides the desired 6-7-6 tricyclic diketoaldehyde, with carbonyl groups at all three positions for eventual C-N bond formation and subsequent elaboration.

SUBMITTER: Pflueger JJ

PROVIDER: S-EPMC6287954 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Magnesiate Addition/Ring-Expansion Strategy To Access the 6-7-6 Tricyclic Core of Hetisine-Type C<sub>20</sub>-Diterpenoid Alkaloids.

Pflueger Jason J JJ Morrill Louis C LC deGruyter Justine N JN Perea Melecio A MA Sarpong Richmond R

Organic letters 20170818 17

A synthetic strategy to access the fused 6-7-6 tricyclic core of hetisine-type C<sub>20</sub>-diterpenoid alkaloids is reported. This strategy employs a Diels-Alder cycloaddition to assemble a fused bicyclic anhydride intermediate, which is elaborated to a vinyl lactone-acetal bearing an aromatic ring in five steps. Aromatic iodination is followed by magnesium-halogen exchange with a trialkyl magnesiate species, which undergoes intramolecular cyclization. Subsequent oxidation provides the desire ...[more]

PMID: 28820600

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