3-Arylindolizines were prepared by one-pot domino reactions from benzyl halides with pyridine (or isoquinoline) and cyclic or acyclic dihalide-substituted electron-deficient alkenes in the presence of potassium carbonate via in situ generated N-ylide intermediate. Both electron-donating and electron-withdrawing groups are tolerated in the aryl ring of benzyl halides. The yields range from moderate to high.
Palladium catalyzed oxidative Suzuki coupling reaction of indolizine at the 3-position using oxygen gas as the only oxidant
作者:Huayou Hu、Yong Liu、Juan Xu、Yuhe Kan、Chao Wang、Min Ji
DOI:10.1039/c4ra03799e
日期:——
Stoichiometric metal oxidant applied in the functionalization of indolizine at the 3-position through C–H activation in a previous report was found to increase the cost of the synthesis and worsen the environmental pollution. In this paper, we developed a Pd(OAc)2/O2 catalytic system with or without ligands for an oxidative Suzuki coupling reaction of indolizine at the 3-position through C–H activation. As reported in the literature, some indolizines dimerized when catalyzed by palladium acetate under ligand-free conditions. However, we found that the dimerization of 2,3-unsubstituted indolizines was inhibited by the addition of ligands. Based on this finding, the arylation of these indolizines can be successfully achieved via a Pd(OAc)/O2 system using picolinic acid as a ligand. 1,2-disubstituted indolizines that do not easily dimerize can react smoothly with arylboronic acids under ligand-free conditions. Furthermore, broad group tolerance was shown in both indolizine and arylboronic acid. Finally, this method has the advantages of mild conditions, a broad array of starting materials and the use of a green oxidant.
Iodine-Mediated Oxidative Cyclization of 2-(Pyridin-2-yl)acetate Derivatives with Alkynes: Condition-Controlled Selective Synthesis of Multisubstituted Indolizines
作者:Lisheng He、Yuzhu Yang、Xiaolan Liu、Guangyan Liang、Chunyan Li、Daoping Wang、Weidong Pan
DOI:10.1055/s-0039-1690229
日期:2020.2
An iodine-mediated oxidative cyclization reaction between 2-(pyridin-2-yl)acetate derivatives and different alkynes has been developed, which provides regioselective and chemoselective syntheses of multiply substituted indolizines under modified reaction conditions. Plausible mechanisms have been proposed to explain the selective syntheses of indolizines. This protocol can be also applied to the stepwise