title: Developing a diastereoselective intramolecular [4+3] cycloaddition of nitrogen-stabilized oxyallyl cations derived from N-sulfonyl-substituted allenamides.
abstract: Efforts toward achieving a practical and diastereoselective intramolecular [4+3] cycloaddition of nitrogen-stabilized oxyallyl cations with tethered dienes are described. Epoxidation of N-sulfonyl substituted allenamides with dimethyldioxirane (DMDO) generates nitrogen-stabilized oxyallyl cations that readily undergo stereoselective [4+3] cycloaddition with dienes. Selectivity is found to depend on the tethering length as well as the stability of the oxyallyl cation intermediate, whether generated from N-carbamoyl- or N-sulfonyl-substituted allenamides. The use of chiral N-sulfonyl-substituted allenamides provided minimal diastereoselectivity in the cycloaddition, while high diastereoselectivity can be achieved with a stereocenter present on the tether. These studies provide further support for the synthetic utility of allenamides.
authors: Division of Pharmaceutical Sciences and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53705, USA.
authors: Andrew G
authors: AG
authors: Lohse
authors: Richard P
authors: RP
authors: Hsung
authors: Mitchell D
authors: MD
authors: Leider
authors: Sunil K
authors: SK
authors: Ghosh
mesh_terms: D000475:Alkenes / Q000737:chemistry*; D000577:Amides / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*; D013057:Spectrum Analysis; D013237:Stereoisomerism; D013379:Substrate Specificity; D013450:Sulfones / Q000737:chemistry*
chemical_list: D000475:Alkenes; D000577:Amides; D006571:Heterocyclic Compounds; D013450:Sulfones; D009584:Nitrogen