Direct Synthesis of Previously Inaccessible Bridgehead Azabicyclics by Intramolecular Cyclization of α-Sulfonamido and α-Sulfonimido Radicals
| Autor: | Silvana M. Leit, Jeffrey D. Schloss, Choon Sup Ra, Judith C. Gallucci, Leo A. Paquette |
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| Rok vydání: | 2001 |
| Předmět: |
Bridged-Ring Compounds
chemistry.chemical_classification Sulfonyl Aza Compounds Sulfonamides Free Radicals Molecular Structure Double bond Chemistry Stereochemistry Organic Chemistry Bridged Bicyclo Compounds Heterocyclic Crystallography X-Ray Ring (chemistry) Triple bond Anti-Infective Agents Cyclization Intramolecular force Electrophile Reactivity (chemistry) Lone pair |
| Zdroj: | The Journal of Organic Chemistry. 66:3564-3573 |
| ISSN: | 1520-6904 0022-3263 |
| DOI: | 10.1021/jo010216z |
| Popis: | Syntheses of the first bridgehead sultams and the only known bridgehead disulfonimide are described. Both approaches capitalize on the electrophilicity of alpha-sulfonyl radicals and their propensity to undergo intramolecular ring closure. Where double bonds are concerned, 5-exo and 6-exo pathways operate preferentially as long as structural strain is not excessive. When the reaction center is a carbon-carbon triple bond, the first cyclization gives rise to vinyl radicals that hold sufficient reactivity to capture solvent benzene. In the case of 45, this sequential reaction leads importantly to the introduction of a styrene functionality sufficiently activated to allow a second ring closure to be kinetically feasible. The solid-state structural features of 12 and 17 have been elucidated by X-ray crystallographic methods. Despite key differences from the norm in the alignment of the nitrogen lone pair relative to the adjacent sulfonyl groups, these compounds exhibit good hydrolytic stability. For 13, generation of the alpha-sulfonamide carbanion is possible and regiospecific oxidation with chromyl acetate has been achieved. |
| Databáze: | OpenAIRE |
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