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Substrate encapsulation: an efficient strategy for the RCM synthesis of unsaturated epsilon-lactones.

ABSTRACT: A facile substrate-encapsulated RCM-based synthesis of 7-membered lactones is reported. Coordination of the alpha,omega-dienyl ester precursor to the bulky Lewis acid (LA) aluminum tris(2,6-diphenylphenoxide) (ATPH) provides a protective extended steric pocket to the olefin moieties, thereby favoring intramolecular RCM over intermolecular ADMET oligomerization. The LA-encapsulated esters undergo ring-closure in the presence of Ru-based olefin metathesis catalysts to give previously difficult-to-access 7-membered beta,gamma- and gamma,delta-unsaturated lactones in good yields.

SUBMITTER: Pentzer EB

PROVIDER: S-EPMC3083066 | biostudies-literature | 2008 Dec

REPOSITORIES: biostudies-literature

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Substrate encapsulation: an efficient strategy for the RCM synthesis of unsaturated epsilon-lactones.

Pentzer Emily B EB Gadzikwa Tendai T Nguyen SonBinh T ST

Organic letters 20081201 24

A facile substrate-encapsulated RCM-based synthesis of 7-membered lactones is reported. Coordination of the alpha,omega-dienyl ester precursor to the bulky Lewis acid (LA) aluminum tris(2,6-diphenylphenoxide) (ATPH) provides a protective extended steric pocket to the olefin moieties, thereby favoring intramolecular RCM over intermolecular ADMET oligomerization. The LA-encapsulated esters undergo ring-closure in the presence of Ru-based olefin metathesis catalysts to give previously difficult-to- ...[more]

PMID: 19053741

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