Iron-Catalyzed Oxidative Coupling of Alkylamides with Arenes through Oxidation of Alkylamides Followed by Friedel-Crafts Alkylation
Iron-Catalyzed Oxidative Coupling of Alkylamides with Arenes through Oxidation of Alkylamides Followed by Friedel-Crafts Alkylation
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DOI：
10.1021/jo102217m
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发表时间：
2011-01-07
影响因子：
3.6
通讯作者：
Hayashi, Tamio
中科院分区：
文献类型：
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作者：
Shirakawa, Eiji;Uchiyama, Nanase;Hayashi, Tamio
FeCL(3) 与 t-BuOOt-Bu 结合作为氧化剂被发现是烷基酰胺氧化成 α-(叔丁氧基)烷基酰胺的有效催化剂。在 N-苯基吡咯烷酮 (1a) 的叔丁氧基化反应中，FeCl(2) 和 CuCl 分别表现出与 FeCl(3) 几乎相同但稍低的活性，而使用 Fe(OTf)(3)、RuCl(3) 或 Zr(OTf)(4) 则没有得到叔丁氧基化产物。发现FeCl(3)也可有效地作为由此获得的α-(叔丁氧基)烷基酰胺进行弗里德尔-克来福特烷基化的催化剂。在催化量的 Fe(OTf)(3)、RuCl(3) 或 Zr(OTf)(4) 存在下，Friedel-Crafts 烷基化反应也顺利进行。相反，FeCl(2)和CuCl对叔丁氧基化表现出一定的活性，但未能促进Friedel Crafts烷基化。在迄今为止检测的过渡金属配合物中，只有 FeCl(3) 对氧化和弗里德尔-克来福特烷基化表现出较高的催化活性。 FeCl(3)的双官能度用于通过串联反应将烷基酰胺与芳烃氧化偶联，该串联反应包括将烷基酰胺氧化成α-(叔丁氧基)烷基酰胺以及随后的Friedel-Crafts烷基化。 FeCl(3) 催化的氧化偶联适用于多种烷基酰胺和芳烃，尽管 FeCl(3) 与 Fe(OTf)(3) 的组合被发现对于低亲核性芳烃的反应有效。 Fe(II)-Fe(III) 催化循环与叔丁氧基化有关，而 Fe(III) 配合物作为路易斯酸则催化 Friedel-Crafts 烷基化。
FeCL(3) in combination with t-BuOOt-Bu as an oxidant was found to be an efficient catalyst for oxidation of alkylamides to alpha-(tert-butoxy)alkylamides. FeCl(2) and CuCl showed, respectively, almost the same and slightly lower activities compared with FeCl(3) in the tert-butoxylation of N-phenylpyrrolidone (1a), whereas no tert-butoxylated product was obtained by use of Fe(OTf)(3), RuCl(3), or Zr(OTf)(4). FeCl(3) was found to be effective also as a catalyst for the Friedel-Crafts alkylation with thus obtained alpha-(tert-butoxy)alkylamides. The Friedel-Crafts alkylation proceeded smoothly also in the presence of a catalytic amount of Fe(OTf)(3), RuCl(3), or Zr(OTf)(4). In contrast, FeCl(2) and CuCl, which showed certain activity toward the tert-butoxylation, failed to promote the Friedel Crafts alkylation. Among the transition metal complexes thus far examined, only FeCl(3) showed high catalytic activities for both the oxidation and the Friedel-Crafts alkylation. The bifunctionality of FeCl(3) was utilized for the oxidative coupling of alkylamides with arenes through a tandem reaction consisting of oxidation of alkylamides to alpha-(tert-butoxy)alkylamides and the following Friedel-Crafts alkylation. The FeCl(3)-catalyzed oxidative coupling is applicable to a wide variety of alkylamides and arenes, though a combination of FeCl(3) with Fe(OTf)(3) was found to be effective for the reaction of arenes with low nucleophilicity. A Fe(II)-Fe(III) catalytic cycle is concerned with the tert-butoxylation, whereas a Fe(III) complex as a Lewis acid catalyzes the Friedel-Crafts alkylation.