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 imine cycloadditions 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 imine reaction components are both generated in situ from readily
不对称金鸡纳生物碱催化的烯酮-N-硫代酰基亚胺环加成反应可提供具有高绝对和相对立体控制的对映体富集的 cis-4,5-二取代 1,3-thiazin-6-one 杂环。这些环加成可以实现对烯醇化的未活化亚胺进行催化不对称直接曼尼希加成的策略。乙烯酮和亚胺反应组分均分别由易得的酰氯和 α-酰氨基砜原位生成。