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Stereoselective Nazarov cyclizations of bridged bicyclic dienones.

ABSTRACT: [reaction: see text] Bridged bicyclic dienones underwent silyl-directed Nazarov cyclization with generally very high diastereoselectivity. In most cases, a strong preference for cyclization to the product with an exo-disposed cyclopentenone was seen. However, the presence of additional unsaturation in the three-carbon bridge of a bicyclo[3.2.1]octadiene system caused complete reversal in selectivity with exclusive formation of the endo-cyclopentenone. The observed selectivities are believed to result from a combination of steric and electronic effects.

SUBMITTER: Mazzola RD

PROVIDER: S-EPMC2529303 | biostudies-literature | 2005 Jun

REPOSITORIES: biostudies-literature

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Stereoselective Nazarov cyclizations of bridged bicyclic dienones.

Mazzola Robert D RD White Timothy D TD Vollmer-Snarr Heidi R HR West F G FG

Organic letters 20050601 13

[reaction: see text] Bridged bicyclic dienones underwent silyl-directed Nazarov cyclization with generally very high diastereoselectivity. In most cases, a strong preference for cyclization to the product with an exo-disposed cyclopentenone was seen. However, the presence of additional unsaturation in the three-carbon bridge of a bicyclo[3.2.1]octadiene system caused complete reversal in selectivity with exclusive formation of the endo-cyclopentenone. The observed selectivities are believed to r ...[more]

PMID: 15957950

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