Highly Regioselective Radical Cyclizations of Allenamides
摘要:
The first radical cyclizations of allenamides are described. These reactions are highly regioselective for the central carbon of the allenic moiety, leading to an efficient preparation of nitrogen heterocycles such as isoquinolines, and carbocycles such as indane and naphthalene derivatives. The exo-cyclization mode could also be achieved in some cases, leading to the synthesis of isoindoles. The feasibility of a tandem radical cyclization using allenamide is also established.
Herein is introduced the application of “super-electron-donor”(SED) 2-azaallylanions in a tandem reduction/radical cyclization/radical coupling/aromatization protocol that enables the rapid construction of isoquinolines. The value of this transition-metal-free method is highlighted by the wide range of isoquinoline ethyl amines prepared with good functional group tolerance and yields. An operationally
Palladium-Catalyzed Intramolecular Arylative Carboxylation of Allenes with CO<sub>2</sub> for the Construction of 3-Substituted Indole-2-carboxylic Acids
作者:Yuki Higuchi、Tsuyoshi Mita、Yoshihiro Sato
DOI:10.1021/acs.orglett.7b01055
日期:2017.5.19
cyclization/carboxylation sequence is thought to be a nucleophilic η1-allylethylpalladium, which reacts with CO2 at the γ-position of palladium. The products obtained could be efficiently converted into 3-substituted indole-2-carboxylate derivatives. One-pot synthesis of strychnocarpine, a β-carboline alkaloid, from the carboxylated product was also demonstrated.
使用PdCl 2 / PAr 3(Ar = C 6 H 4 - p -CF 3)和ZnEt 2在CO的1个大气压下,分子内方式进行的烯丙基的芳基羧化反应以高产率得到相应的β,γ-不饱和羧酸。2。环化/羧化序列的中间被认为是亲核η 1 -allylethylpalladium,其发生反应用CO 2在钯的γ位置。所获得的产物可以有效地转化为3-取代的吲哚-2-羧酸酯衍生物。还证实了从羧化产物一锅法合成苯乙烯基香菜碱(一种β-咔啉生物碱)。
Synthesis of Heterobenzyl Sulfoxides Enabled by Palladium-Catalyzed Allylic Alkylation of Sulfenate Anions with Allenamides
作者:Lei Wang、Shuaijie Wu、Shuting Zhang、Qianqian Hu、Qiang Wang、Jing Sun、Ying Han、Chao-Guo Yan
DOI:10.1021/acs.joc.2c01998
日期:2022.11.4
A highly efficient palladium-catalyzed allenamide allylic alkylation of sulfenate anions under mild conditions is demonstrated. The present methodology provides a practical protocol to access various sulfoxide-containing heterocyclic compounds. The salient features of this transformation include a broad substrate scope, good functional group tolerance, easy to scale-up, and ready synthetic transformation