Catalytic Asymmetric [4 + 2] Cycloadditions of Ketenes and <i>N</i>-Thioacyl Imines: Alternatives for Direct Mannich Reactions of Enolizable Imines
作者:Xuan Xu、Kan Wang、Scott G. Nelson
DOI:10.1021/ja074845n
日期:2007.9.1
cinchona alkaloid-catalyzed ketene-N-thioacyl iminecycloadditions afford enantioenriched cis-4,5-disubstituted 1,3-thiazin-6-one heterocycles with high absolute and relative stereocontrol. These cycloadditions enable a strategy for executing catalytic asymmetric direct Mannich additions to enolizable, unactivated imines. The ketene and iminereaction components are both generated in situ from readily