Palladium catalyzed carbonylative annulation of the C(sp<sup>2</sup>)–H bond of <i>N</i>,1-diaryl-1<i>H</i>-tetrazol-5-amines and <i>N</i>,4-diaryl-4<i>H</i>-triazol-3-amines to quinazolinones
as both directing as well as intramolecular nucleophiles. The catalytically active C–H activated intermediate dimeric Pd complex was isolated and characterized which on exposure to CO gas gave the corresponding tetrazole fused quinazolinone derivative. On the basis of isolation of the intermediate and observed kinetic isotope effects, a mechanism has been proposed for the C–H activated direct carbonylative
A variety of functionalities, including the whole range of halogen substituents, are tolerated in the title reaction, an intramolecular approach for the construction of a multisubstituted indole skeleton from readily available enaminones (see scheme; phen=1,10‐phenanthroline). The indole products are also prepared directly in high yield from α,β‐ynones and primary amines.
A Pd(II)-catalyzed ortho-selective halogenation of N-aryl ring of N,1-diaryl-1H-tetrazol-5-amine has been described employing N-halosuccinimide as a halogen source viaC–H bond activation. The present work features 5-aminotetrazole, as a directing group, for the chemo- and regioselectiveC–H halogenation of arenes. The kinetic isotope study (kH/kD = 2.9) suggests that the cleavage of the C–H bond takes
N,1-二芳基-1 H-四唑-5-胺的N-芳基环的Pd(II)催化邻位选择性卤化已通过N-卤代琥珀酰亚胺通过CH键进行卤素活化。目前的工作以5-氨基四唑为导向基团,用于芳烃的化学和区域选择性CH卤代。动力学同位素研究(k H / k D = 2.9)表明,CH键的裂解发生在速率确定步骤中。该协议的范围和机制已得到证明。
Catalytic Coupling of Haloolefins with Anilides
作者:Vladimir G. Zaitsev、Olafs Daugulis
DOI:10.1021/ja050366h
日期:2005.3.1
A strategy in which C-H activation reactions promoted by Pd(II) have been combined with beta-heteroatom elimination to create a catalytic cycle achieving the arylation of haloacrylates is reported. The catalytic cycle can be subdivided into four parts: (1) C-H activation; (2) the functionalization step, migratory insertion of the olefin into a metal-carbon bond; (3) beta-heteroatom elimination; and (4) exchange of metal halide (if X = halogen) for a less coordinating anion. In this catalytic cycle, the oxidation state of the metal does not change, and an oxidant is not required. The method is more functional group tolerant compared with the existing alkene-arene coupling methods based on electrophilic C-H activation.
作者:Kanagaraj Naveen、Paramasivan Thirumalai Perumal、Deug-Hee Cho
DOI:10.1021/acs.orglett.9b01543
日期:2019.6.7
A Pd-catalyzed domino process involving a double norbornene insertion/annulation reaction was developed for the expeditious synthesis of overcrowded olefins. In this one-pot reaction, four new C–C bondformations were achieved by three consecutive Heck carbopalladations and C–H activation across the C≡C triple bond of 2-alkynyl bromobenzenes with two norbornene rings via a reactive vinylic-Pd(II) species