by the intermediacy of N-acyliminium species. A similar process applied to lactams 21b–25b affords the pyrrolizidine type compounds 26–35 through consecutive azonium-Cope rearrangement and N-acyliminium ringclosure. Additional results are concerned with the use of aromatic rings as π-nucleophiles.
Tuning Reactivity and Chemoselectivity in Electron Transfer Initiated Cyclization Reactions: Applications to Carbon−Carbon Bond Formation
作者:John R. Seiders、Lijun Wang、Paul E. Floreancig
DOI:10.1021/ja029139v
日期:2003.3.1
demonstrate that the scope of our electrontransfer initiated cyclization reaction can be significantly broadened by exploiting the relationship between the oxidation potentials of homobenzylic ethers and the mesolytic benzylic carbon-carbonbond dissociation energies of their radical cations. By lowering the oxidation potential of the electrophore and the benzylic carbon-carbonbond dissociation energy, we
Catalytic Scaffolding Ligands: An Efficient Strategy for Directing Reactions
作者:Thomas E. Lightburn、Michael T. Dombrowski、Kian L. Tan
DOI:10.1021/ja803011d
日期:2008.7.1
that promotes branch and diastereoselectivehydroformylation of terminal olefins as well as the regio- and diastereoselectivehydroformylation of disubstituted olefins is reported. It is shown that the ligand covalently and reversibly bonds to the substrate, allowing for directedhydroformylation. As the substrate ligand interaction is dynamic, hydroformylations are catalytic in ligand and do not require