Department of Organic Chemistry, Indian Institute of Science, Bangalore 560 012, Karnataka, India.
J Org Chem. 2021 Mar 19;86(6):4625-4637. doi: 10.1021/acs.joc.1c00048. Epub 2021 Mar 9.
[4 + 3] annulation of primary and secondary benzamide and cinnamamide derivatives using allyl alcohol as a coupling partner catalyzed by Rh(III) is reported, where Rh(III) is playing a dual role of an oxidant and a catalyst for C-H activation. The Rh-catalyst oxidizes allyl alcohol to its carbonyl derivative, and the in situ-generated carbonyl compound reacts with benzamide in the presence of the Rh-catalyst, forming the corresponding alkylated products. Mechanistic studies show that AgSbF is also playing a dual role. Apart from being a halide scavenger, AgSbF catalyzes the cyclization of the alkylated product, forming the desired lactam. The current method has good synthetic application and is useful for synthesizing a few biologically active compounds that can act as the dopamine D receptor ligand, including berberine-like analogues. The deuteration study and control experiments helped us to propose the mechanism.
[4 + 3] 环化反应使用烯丙醇作为偶联试剂，对一级和二级苯甲酰胺和肉桂酰胺衍生物进行催化，反应中 Rh(III) 同时扮演氧化剂和 C-H 活化催化剂的双重角色。Rh 催化剂将烯丙醇氧化为其羰基衍生物，然后在 Rh 催化剂的存在下，生成的羰基化合物与苯甲酰胺反应，形成相应的烷基化产物。机理研究表明，AgSbF 也发挥了双重作用。除了作为卤化物清除剂外，AgSbF 还可以催化烷基化产物的环化反应，形成所需的内酰胺。该方法具有良好的合成应用价值，可用于合成一些具有生物活性的化合物，如作为多巴胺 D 受体配体的黄连素类似物。氘代研究和对照实验帮助我们提出了该反应的机理。
