钯催化条件下形成碳硫键合成多氯代二苯硫醚

以四三苯基膦钯为催化剂,碳酸铯为碱,氯代碘苯和氯代苯硫酚在甲苯中加热到112℃回流16 h,发生偶联反应形成C—S—C硫醚键,合成了23个多氯代二苯硫醚系列化合物,产物均经IR,1H NMR表征,并测定熔点.反应操作简单,收率良好,条件温和,是一种较好的合成多氯代二苯硫醚化合物的新方法.     

Recent Advances in Carbon-Nitrogen/Carbon-Oxygen Bond Formation Under Transition-Metal-Free Conditions

Carbon-heteroatom bond formation under transition-metal free conditions provides a powerful synthetic alternative for the efficient synthesis of valuable molecules. In particular, C−N and C−O bonds are two important types of carbon-heteroatom bonds. Thus, continuous efforts have been deployed to develop novel C−N/C−O bond formation methodologies involving various catalysts or promoters under TM-free conditions, which enables the synthesis of various functional molecules comprising C−N/C−O bonds in a facile and sustainable manner. Considering the significance of C−N/C−O bond construction in organic synthesis and materials science, this review aims to comprehensively present selected examples on the construction of C−N (including amination and amidation) and C−O (including etherification and hydroxylation) bonds without transition metals. Besides, the involved promoters/catalysts, substrate scope, potential application and possible reaction mechanisms are also systematically discussed.     

C-Phosphorylation of Compounds with the Electron-Rich Double Carbon-Nitrogen Bond

Abstract

C-phosphorylation of N,N-dimethylhydrazones and N,N-dimethyl-N′-arylamidines by phosphorus tribromide was first accomplished. It directs to the formation of novel types of functional P(III) derivatives (1–3)     

Take the Right Catalyst: Palladium-Catalyzed C-C, C-N, and C-O Bond Formation on Chloroarenes

Unreactive chloroarenes have been outwitted: The key to successful C-C, C-N, and C-O bond formation on chloroarenes is the development and optimization of suitable catalysts. Electron-rich alkylphosphanes are mandatory as ligands in these palladium-catalyzed reactions.     

Azine Synthesis via Nitrogen-Nitrogen Bond Formation

Imine anions, generated by reaction of nitrites with organometallic reagents, are dimerized to form symmetrical azines through the use of CuI and t-butyl peroxybenzoate.     

Palladium-Catalyzed Synthesis of Tetrahydrocarbazoles

The synthesis of tetrahydrocarbazoles from bromoenaminones derived from β-diketones is described. The reaction proceeds by intramolecular cyclization of bromoenaminones involving arylpalladium complexes.     

Direct Crystallization of Diamine Radical Cations: Carbon-Nitrogen Bond Formation from the Reaction of Triphenylamine with TiCl4, TiBr4, or SnCl4 versus Carbon-Carbon Bond Formation with SbCl5**

Direct synthesis of diamine radical cations in crystalline form proceeding through oxidation of triphenylamine followed by the formation of a new C−N bond is reported. Although the oxidative coupling of triphenylamine is well studied, diamine products are rarely captured in their radical cation state. The neutral diamine most frequently obtained from this reaction pathway is N,N,N’,N’-tetraphenylbenzidine. Herein, the capture of radical cations of diamines in crystalline form in one step starting with neutral triphenylamine was demonstrated, and the formation of two products (the radical cations of N,N,N′,N′-tetraphenyl-1,4-benzenediamine or N,N,N′,N′-tetraphenylbenzidine) depending on the oxidizing agent used was observed. The radical species are characterized by single-crystal X-Ray diffraction, electron paramagnetic resonance spectroscopy, and optical spectroscopy.     

Palladium-Catalyzed C-C Bond Activation/Suzuki Reaction of Methylenecyclobutanes

Main observation and conclusion Transition-metal catalyzed C-C bond activation is a formidable challenge owing to the high bond energy.We report here a novel pa...     

Diastereoselective Cyclobutenol Synthesis: A Heterogeneous Palladium-Catalyzed Oxidative Carbocyclization-Borylation of Enallenols

A highly selective and efficient oxidative carbocyclization/borylation of enallenols catalyzed by palladium immobilized on amino-functionalized siliceous mesocellular foam (Pd-AmP-MCF) was developed for diastereoselective cyclobutenol synthesis. The heterogeneous palladium catalyst can be recovered and recycled without any observed loss of activity or selectivity. The high diastereoselectivity of the reaction is proposed to originate from a directing effect of the enallenol hydroxyl group. Optically pure cyclobutenol synthesis was achieved by the heterogeneous strategy by using chiral enallenol obtained from kinetic resolution.     

C-F Bond Formation for the Synthesis of Aryl Fluorides

A selection of carbon-fluorine bond-forming reactions is presented with particular focus on transition metal-mediated fluorination. A brief summary of conventional fluorination reactions is followed by a discussion of fluorination reactions mediated by palladium and silver. Investigations into the mechanism as well as the conceptual difficulty associated with transition metal-mediated carbon-fluorine bond formation are presented.     

The Efficient Palladium-Catalyzed Selective t Synthesis of Benzenesulfonic Acids

α-Chloroalkyl aryl ethers has been obtained in good yields from phenols and aryl α-chloroalkyl sulfides.     

ZrCl4-Catalyzed C-O Bond to C-N Bond Formation: Synthesis of 1,2,3-Triazoles and Their Biological Evaluation

A simple and efficient protocol was developed for the synthesis of aryl azides directly from aryl carbinols using ZrCl₄ as a Lewis acid catalyst. The azides were converted to novel triazoles under click reaction conditions, which were evaluated for their antimicrobial activity against various strains.     

Efficient Palladium-Catalyzed Cyclotrimerization of Arynes: Synthesis of Triphenylenes

Found at the core of many discotic liquid crystals , triphenylenes can now be synthesized efficiently by the palladium-catalyzed trimerization of arynes, including those containing donor and acceptor substituents [Eq. (a); R=OMe, F].     

Palladium-Catalyzed Aminomethylation of Nitrodienes and Dienones via Double C-N Bond Activation

A new strategy for the generation of the active Pd-alkyl species from aminal via C-N bond activation has been established,in which the formation of zwitterionic...     

Synthesis of Clomid Using Palladium-Catalyzed Cross-Coupling

Two methods of choice for the synthesis of clomid, a tetrasubstituted olefin with antiestrogenic activity, are described. The key reaction is hydroalumination of diphenylacetylene followed by C-C cross-coupling using catalytic amount of Pd⁰.     

Hypervalent Iodine in Synthesis XXXIV: Palladium-Catalyzed Coupling Reaction of o-Hydroxyarylaldehydes with Hypervalent Iodonium Salts Via Cleavage of the Aldehyde C-H Bond

A novel way of preparation for o-hydroxyarylketones with mild conditions and good yields by palladium-catalyzed coupling reaction of o-hydroxyarylaldehydes with hypervalent iodonium salts via the cleavage of the aldehyde C-H bond has been reported.     

Pd催化交叉偶联P-C键形成反应

近30年来,Pd催化交叉偶联形成P-C键的反应在药物、催化剂配体、阻燃剂和高分子材料等领域受到普遍重视。本文介绍了Pd催化交叉偶联反应形成P-C键的方法,以及利用该法制备有机膦化合物的研究进展。作为反应底物的磷亲核试剂包括亚磷酸二烷基酯、亚膦酸酯、次膦酸酯、氧化膦、伯或仲膦、三芳基膦、亚磷酸三烷基酯、膦-硅(锡)化合物和膦-硼烷复合物等,参与偶联反应的亲电试剂包括卤代烯烃、卤代芳烃、三氟甲磺酸烯基酯、三氟甲磺酸芳基酯、乙烯基硼酸酯等,并对反应机理、反应条件和反应的影响因素进行了探讨。