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Intramolecular oxyallyl-carbonyl (3 + 2) cycloadditions.

ABSTRACT: Cycloadditions involving oxyallyl intermediates typically require an electron-rich diene or alkene, but we have discovered the first examples of the cycloaddition of heteroatom-stabilized oxyallyls onto carbonyl groups. An oxazolidinone-substituted oxyallyl undergoes chemoselective (3 + 2) cycloaddition onto the carbonyl group of a tethered dienone in preference to formation of the expected (4 + 3) cycloadduct. Density functional theory calculations indicated that the (3 + 2) cycloaddition takes place through a concerted, highly asynchronous mechanism. The transition state features simultaneous interactions of the oxyallyl LUMO with the carbonyl ? and lone-pair orbitals, making this reaction "hemipseudopericyclic" (halfway between purely pericyclic and purely pseudopericyclic). Further (3 + 2) cycloadditions involving tethered phenyl ketones and a tethered enone were predicted theoretically and verified experimentally.

SUBMITTER: Krenske EH

PROVIDER: S-EPMC3642281 | biostudies-literature | 2013 Apr

REPOSITORIES: biostudies-literature

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Intramolecular oxyallyl-carbonyl (3 + 2) cycloadditions.

Krenske Elizabeth H EH He Shuzhong S Huang Jian J Du Yunfei Y Houk K N KN Hsung Richard P RP

Journal of the American Chemical Society 20130401 14

Cycloadditions involving oxyallyl intermediates typically require an electron-rich diene or alkene, but we have discovered the first examples of the cycloaddition of heteroatom-stabilized oxyallyls onto carbonyl groups. An oxazolidinone-substituted oxyallyl undergoes chemoselective (3 + 2) cycloaddition onto the carbonyl group of a tethered dienone in preference to formation of the expected (4 + 3) cycloadduct. Density functional theory calculations indicated that the (3 + 2) cycloaddition takes ...[more]

PMID: 23544997

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