| Attributs | Valeurs |
|---|
| type
| |
| Is Part Of
| |
| Subject
| |
| Title
| - Synthesis of Bicyclic Pyrane Derivatives via Tungsten-Mediated[3 + 3] Cycloaddition of Epoxides with Tethered Alkynes
|
| has manifestation of work
| |
| related by
| |
| Author
| |
| Abstract
| - Propargyltungsten compounds bearing a tethered epoxide were prepared in short steps from readilyavailable materials. In the presence of various Lewis acids, BF3·Et2O catalysts (25 mol %) mosteffectively promote the [3 + 3] cycloaddition of the epoxide with its tethered propargyltungstengroup, delivering bicyclic pyranyltungsten compounds in reasonable yields. This cyclization proceedshighly diastereoselectively with tolerance of various functional groups. The stereochemical outcomeindicates that the cycloaddition is initiated by the ring opening of the epoxides via an exo-attackof the propargyltungsten group. The resulting pyranyltungsten organometallics were demetalatedto yield various bicyclic pyranyl derivatives using different oxidants. This new method provides ashort enantiospecific synthesis of bicyclic oxygen compounds if chiral epoxide is used in thecyclization. A mechanistic model is presented to rationalize the reaction pathway of this [3 + 3]cycloaddition.
|
| article type
| |
| is part of this journal
| |
