Brucine N-oxide-catalyzed Morita–Baylis–Hillman reaction of vinyl ketones: a mechanistic implication of dual catalyst system with proline
作者:Kyungsoo Oh、Jian-Yuan Li、Jinhyang Ryu
DOI:10.1039/c003667f
日期:——
The brucine N-oxide promoted Morita–Baylis–Hillman (MBH) reaction of vinyl ketones with aldehydes has been achieved. The corresponding asymmetric version of MBH reaction was also investigated, and the electron-deficient aryl aldehydes have emerged as suitable reaction partners for vinyl ketones; where proline was employed as a co-catalyst. In this dual catalyst system, proline is believed to form iminium
原始的N氧化物促进了Morita–Baylis–Hillman(MBH)已经实现了乙烯基酮与醛的反应。对应的不对称版本MBH还对反应进行了研究,并且出现了缺电子的芳基醛作为乙烯基酮的合适反应伙伴。在哪里脯氨酸被用作助催化剂。在这种双重催化剂系统中,脯氨酸认为N-氧化物与缺电子的芳基醛形成亚胺中间体,而N-氧化物活化乙烯基酮以通过共轭加成提供烯醇化物。结合这两种中间体后,通过控制速率确定步骤可以得到高对映选择性的MBH产物。H桥接的椅子状过渡状态。本质上,结果MBH发现产物醇类干扰中间体,烯醇化物和脯氨酸亚胺鎓中间体两者的形成,因此观察到的产物的对映选择性在进一步反应转化时减弱,可能是由于自催化作用。本研究为衍生自缺电子的芳基醛和脯氨酸。