Tandem Inter [4 + 2]/Intra [3 + 2] Cycloadditions of Nitroalkenes. Asymmetric Synthesis of Highly Functionalized Aminocyclopentanes Using the Bridged Mode (β-Tether) Process

An asymmetric, tandem inter [4 + 2]/intra [3 + 2] bridged mode (β-tether) cycloaddition of nitroalkenes has been developed. This new sequence involves the Lewis acid-promoted [4 + 2] cycloaddition of nitro olefins with enantiopure 1-alkoxy-1,4-dienes. The resulting nitronates, bearing a C(5) tethere...

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Veröffentlicht in:Journal of organic chemistry 1998-09, Vol.63 (18), p.6178-6195
Hauptverfasser: Denmark, Scott E, Dixon, Julie A
Format: Artikel
Sprache:eng
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Zusammenfassung:An asymmetric, tandem inter [4 + 2]/intra [3 + 2] bridged mode (β-tether) cycloaddition of nitroalkenes has been developed. This new sequence involves the Lewis acid-promoted [4 + 2] cycloaddition of nitro olefins with enantiopure 1-alkoxy-1,4-dienes. The resulting nitronates, bearing a C(5) tethered dipolarophile, undergo thermal, intramolecular [3 + 2] cycloaddition to afford stable tricyclic nitroso acetals, which can be subsequently reduced to provide interesting aminocyclopentanes. Thus, in three steps, highly functionalized, enantiomerically enriched aminocyclopentanes can be constructed with good yield and high ee. Additionally, the Lewis acid was found to impart a remarkable influence on the stereochemical outcome of the [4 + 2] cycloaddition.
ISSN:0022-3263
1520-6904
DOI:10.1021/jo9802170