The Tandem Inter [4+2]/[3+2] Cycloadditions of Nitroalkenes: The Bridged-Mode

279 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1998.In continuing investigations, an asymmetric variant of the tandem inter $\lbrack 4 + 2\rbrack$/intra $\lbrack 3 + 2\rbrack$ bridged mode ($\beta$-tether) cycloaddition of nitroalkenes has been developed. This new sequence involves the Lewis-acid-promoted $\lbrack 4 + 2\rbrack$ cycloaddition of a variety of nitro olefins with 1-alkoxy-1,4-pentadienes derived from (1R,2S)-phenylcyclohexanol. Intramolecular $\lbrack 3 + 2\rbrack$ cycloadditions afforded stable nitroso acetals that were reduced using nickel boride to provide enantiomerically enriched aminocyclopentanes in good yields and high enantiomeric excess. Additionally, the Lewis acid employed in the $\lbrack 4 + 2\rbrack$ cycloaddition was found to impart a remarkable influence on the stereochemical outcome of the tandem sequence.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD