title: Tandem Inter [4 + 2]/Intra [3 + 2] Cycloadditions of Nitroalkenes. The Bridged Mode (beta-Tether).
abstract: A new variation of the tandem inter [4 + 2]/intra [3 + 2] cycloaddition of nitroalkenes has been developed. This method involves the Lewis acid-promoted [4 + 2] cycloaddition of nitro olefins 12 with 1-alkoxy-1,4-dienes 3. The resulting nitronates 13, bearing a C(5) tethered dipolarophile, undergo thermal, intramolecular [3 + 2] cycloaddition to afford stable tricyclic nitroso acetals 14, which can be subsequently reduced to unveil a new carbocycle 16. Thus, in three steps, highly functionalized aminocyclopentanes can be stereoselectively constructed in high yield.
authors.affiliation: Roger Adams Laboratory, Department of Chemistry, University of Illinois Urbana, Illinois 61801.
authors.forename: Scott E.
authors.initials: SE
authors.lastname: Denmark
authors.forename: Julie A.
authors.initials: JA
authors.lastname: Dixon