首次以吡咯烷作为有机催化剂，实现亚硝基烯烃的催化逆电子需求杂环狄尔斯-阿尔德反应。
The first catalytic inverse-electron demand hetero-Diels-Alder reaction of nitroso alkenes using pyrrolidine as an organocatalyst.
作者信息
Wabnitz Tobias C, Saaby Steen, Jørgensen Karl Anker
机构信息
The Danish National Research Foundation: Center for Catalysis, Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark.
出版信息
Org Biomol Chem. 2004 Mar 21;2(6):828-34. doi: 10.1039/b316518c. Epub 2004 Feb 16.
The first catalytic inverse-electron demand hetero-Diels-Alder reaction of nitroso alkenes has been developed. Nitroso alkenes were generated in situ from alpha-halooximes and underwent [4 + 2]-cycloadditions with enamines as dienophiles formed from aldehydes and pyrrolidine (10 mol%) as an organocatalyst. The presence of a suitable heterogeneous buffer system was found to be essential and best results were obtained with sodium acetate trihydrate. The resulting 5,6-dihydro-4H-oxazines were obtained in moderate to good yields under mild reaction conditions. A catalytic cycle has been proposed and evidence for the cycloaddition mechanism has been obtained. Moderate asymmetric induction (42% ee) was observed when a chiral secondary amine was used.
已开发出首例亚硝基烯烃的催化逆电子需求杂环狄尔斯-阿尔德反应。亚硝基烯烃由α-卤代肟原位生成，并与作为亲双烯体的烯胺发生[4 + 2]环加成反应，烯胺由醛和作为有机催化剂的吡咯烷（10 mol%）形成。发现合适的非均相缓冲体系的存在至关重要，使用三水合醋酸钠可获得最佳结果。在温和的反应条件下，所得的5,6-二氢-4H-恶嗪以中等至良好的产率得到。提出了一个催化循环，并获得了环加成机理的证据。当使用手性仲胺时，观察到中等程度的不对称诱导（42% ee）。
Zotero 插件