Download PDF
Synfacts 2009(4): 0411-0411  
DOI: 10.1055/s-0028-1087868
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart ˙ New York

Inverse Electron Demand HDA of 2-Alkenoyl N-Oxides

Contributor(s): Hisashi Yamamoto, Joshua N. Payette
S. Barroso, G. Blay*, M. C. Muñoz, J. R. Pedro*
Universitat de València and Universitat Politècnica de València, Spain
Further Information

Publication History

Publication Date:
23 March 2009 (online)

    Permissions and Reprints

Significance

In related studies Evans and Jørgensen have reported that chiral BOX-Cu(II) complexes efficiently promote inverse electron demand HDA reactions of α,β-unsaturated acyl phosphonates and esters with electron-rich al­kenes. In the present work, the authors apply this system to related reactions of vinyl ethers and 2-alkenoylpyridine N-oxides to obtain dihydropyran derivates in excellent yields and enantioselectivities. Additionally, various vinyl ethers, N-vinyllactams, and vinylsulfides were compatible under the reaction conditions. Conducting the reaction at low temperatures (-20 to -40 ˚C) was crucial for obtaining high selectivities as higher temperatures resulted in a large diminution in ee values.