Intramolecular C-H Insertion Reactions of ($\eta^5$-Cyclopentadienyl)dicarbonyliron Carbene Complexes: Scope of the Reactions and Application to the Synthesis of (\pm)-Sterpurene and (\pm)-Pentalenene

Ishii, Shingo and Zhao, Shikai and Mehta, Goverdhan and Knors, Christopher J and Helquist, Paul (2001) Intramolecular C-H Insertion Reactions of ($\eta^5$-Cyclopentadienyl)dicarbonyliron Carbene Complexes: Scope of the Reactions and Application to the Synthesis of (\pm)-Sterpurene and (\pm)-Pentalenene. In: Journal of Organic Chemistry, 66 (10). pp. 3449-3458.

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Official URL: http://pubs.acs.org/doi/abs/10.1021/jo001792i

Abstract

($\eta^5$-Cyclopentadienyl)dicarbonyliron carbene complexes, $[(\eta^5-C_5H_5)(CO)_2Fe=CHR]+BF_4-$, are generated as reactive intermediates from thioether derivatives, $(\eta5-C_5H_5)(CO)_2FeCHR)SPh$, by Salkylation with trimethyloxonium tetrafluoroborate and loss of thioanisole. The carbene complexes undergo intramolecular C-H insertion into appropriately situated side chains to form cyclopentane derivatives. The reaction has been developed into a general procedure employing cycloalkanones as scaffolds bearing the iron carbene moieties and the side chains at C(2) and C(3), respectively. The products of the intramolecular insertion reactions are substituted bicyclo[n.3.0]alkanones. The scope and limitations of the reaction are described. The reaction is applied to a total synthesis of sterpurene and to a formal synthesis of pentalenene. Overall, this approach to cyclopentane annulation complements the related metal-catalyzed insertion reactions of diazocarbonyl compounds, which are also believed to occur via metal carbene complexes.

Item Type: Journal Article Copyright for this article belongs to American Chemical Society. Division of Chemical Sciences > Organic Chemistry 01 Feb 2005 08 Jan 2013 05:51 http://eprints.iisc.ernet.in/id/eprint/2684