Wool-anchored Pd(OAc)₂ complex: a highly active and reusable catalyst for desulfurative coupling reactions

Abstract

A biomacromolecule-anchored palladium complex, wool-Pd(OAc) 2 complex, was prepared and characterized by IR, XPS, SEM and ICP. The new complex was used as a catalyst for the Liebeskind-Srogl desulfurative coupling reactions of pyrimidin-yl thioether derivatives with terminal alkynes and aryl boronic acids, respectively. Products were isolated in moderate to excellent yields. When 10 2-(phenylthio)-1,4-dihydropyrimidine derivatives were reacted with terminal alkynes and carboxyl acids, a domino reaction process was revealed. In these reactions, this novel and efficient catalyst was capable to be reused for at least nine rounds, and performed an endurable activity as well as the wide tolerance of the substrates.Abstract: A biomacromolecule-anchored palladium complex, wool-Pd(OAc) 2 complex, was used as a catalyst for the Liebeskind-Srogl desulfurative coupling reactions of pyrimidin-yl thioether derivatives with terminal alkynes and arylboronic acids, respectively. Products were isolated in moderate to excellent yields. Notably, when 2-(phenylthio)-1,4-dihydropyrimidine derivatives were reacted with terminal alkynes and carboxyl acids, a domino reaction process was revealed. In these reactions, this novel and efficient catalyst was capable to be reused for at least nine rounds, and performed an endurable activity as well as the wide tolerance of the substrates.

The Liebeskind–Srogl Cross‐Coupling Reaction and its Synthetic Applications

“…In 2015, the Wang group prepared a type of biomacromolecule‐anchored palladium complex, wool−P(OAc) 2 , and applied it to the Liebeskind–Srogl cross‐coupling reaction between pyrimidinyl thioether derivatives and terminal alkynes or aryl boronic acids to afford the corresponding products in good yields (Scheme ) . More importantly, this new catalyst was capable of being reused in at least nine successive runs with durable performance.…”

Hypercrosslinked Polymer Platform-Anchored Single-Site Heterogeneous Pd–NHC Catalysts for Diverse C–H Functionalization

“…Moreover, these values are also indicative of the formation of Pd II −NHC bonds from the reaction of the imidazolium moieties present in the HCPs and Pd(OAc) 2 , in line with previous reports on similar heterogenized Pd II −NHC systems. 7,9a,16−18 In comparison with the Pd 3d core-level binding energies in Pd(OAc) 2 (338.4−338.7 eV for 3d 5/2 and 343.8 eV for 3d 3/2 ), 12,16,19 the respective binding energy values in HCP-B-Me NHC-Pd, HCP-B-Bn NHC-Pd, and HCP-TPM-Me NHC-Pd systems shifted to lower energies by 0.9−1.5 eV for the 3d 5/2 level and by 1.2−1.5 eV for the 3d 3/2 level. It signified the enhancement of electron density at the Pd II center caused due to the strong electron donation from the NHC ligands in the HCP-Pd systems.…”

Visible‐Light‐Promoted Synthesis of Arylthiopyrimidines through Oxidative Coupling of Pyrimidine Disulfides with Arylhydrazines

“…Meanwhile, our laboratory has devoted to the research of pyrimidine compounds on construct CÀ C, CÀ N, and CÀ S bonds via a series of metal catalysis CÀ S and SÀ S bonds cleavage. [14,18] Due to the advantages of stable properties, symmetrical structure and easy handling, [19] dithiopyrimidines are commonly used to build CÀ S bonds by SÀ S bonds cleavage. [20] Thus, our group mainly developed the synthesis of poly-substituted 2-arylthiopyrimidines by the following methods: (a) nucleophilic substitution reactions of pyrimidine sulfonates with thiophenols via CÀ O bonds cleavage; [18a] (b) copper-or iron-catalyzed CÀ S crosscoupling of pyrimidine disulfides with arylboronic acid or sensitive metal reagents (Scheme 1).…”

“…Meanwhile, 3,4,5‐trimethoxyphenylthiopyrimidine as combretastatin A‐4 analog might have anticancer activity against MCF‐7 breast cell line [13] . Furthermore, pyrimidine thioethers can also be utilized as synthetic intermediates to construct new bonds like C−C bonds through the cleavage of the C−S bonds [14] . Based on pyrimidine thioethers significance in such a wide range of fields, it is still necessary for its compound structures and synthesis methods to innovate.…”

“…Before Sohn, only Karade [17] revealed that 3,4‐dihydropyrimidine‐2(1H)‐thiones and diaryliodonium salts form tetrasubstituted pyrimidine sulfides in the presence of CuO nanoparticles. Meanwhile, our laboratory has devoted to the research of pyrimidine compounds on construct C−C, C−N, and C−S bonds via a series of metal catalysis C−S and S−S bonds cleavage [14,18] . Due to the advantages of stable properties, symmetrical structure and easy handling, [19] dithiopyrimidines are commonly used to build C−S bonds by S−S bonds cleavage [20] .…”