The cores of many types of polymers, ligands, natural products, and pharmaceuticals contain biaryl or substituted aromatic structures, and efficient methods of synthesizing these structures are crucial to the work of a broad spectrum of organic chemists. Recently, Pd-catalyzed carbon−carbon bond-forming processes, particularly the Suzuki−Miyaura cross-coupling reaction (SMC), have risen in popularity for this purpose. The SMC has many advantages over other methods for constructing these moieties, including mild conditions, high tolerance toward functional groups, the commercial availability and stability of its reagents, and the ease of handling and separating byproducts from its reaction mixtures. Until 1998, most catalysts for the SMC employed triarylphosphine ligands. More recently, new bulky and electron-rich phosphine ligands, which can dramatically improve the efficiency and selectivity of such cross-coupling reactions, have been introduced. In the course of our studies on carbon−nitrogen bond-formi...

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Palladium-Catalyzed Suzuki-Miyaura Cross-coupling Reactions Employing Dialkylbiaryl Phosphine Ligands

Transition-Metal-Catalyzed C−S, C−Se, and C−Te Bond Formation via Cross-Coupling and Atom-Economic Addition Reactions

Palladium-catalyzed cross-coupling reactions enable organic chemists to form C-C bonds in targeted positions and under mild conditions. Although phosphine ligands have been intensively researched, in the search for even better cross-coupling catalysts attention has recently turned to the use of N-heterocyclic carbene (NHC) ligands, which form a strong bond to the palladium center. PEPPSI (pyridine-enhanced precatalyst preparation, stabilization, and initiation) palladium precatalysts with bulky NHC ligands have established themselves as successful alternatives to palladium phosphine complexes. This Review shows the success of these species in Suzuki-Miyaura, Negishi, and Stille-Migita cross-couplings as well as in amination and sulfination reactions.

The development of bulky palladium NHC complexes for the most-challenging cross-coupling reactions.

A general catalytic system for the coupling of aryl halides and sulfonates with thiols based on the use of the CyPF-t-Bu ligand (1) is reported. The reactions catalyzed by complexes of 1 occur in excellent yields with broad scope and exhibit extraordinary turnover numbers and high tolerance of functional groups. Turnover numbers usually exceed those of previous catalysts by 2 or 3 orders of magnitude. In addition, the reactions of aryl tosylates with alkane thiols to form aryl sulfides are reported for the first time. Finally, the synthesis of a diarylsulfide from two bromoarenes was accomplished using a hydrogen sulfide surrogate.

A general and long-lived catalyst for the palladium-catalyzed coupling of aryl halides with thiols.

In this update, progress made in the last decade for the selective catalytic hydrogenation of nitroarenes in the presence of other reducible functions is reviewed. The main focus is on catalytic systems capable of reducing nitro groups with very high chemoselectivity in substrates containing carbon–carbon or carbon–nitrogen double or triple bonds, carbonyl or benzyl groups, and multiple Cl, Br, or I substituents. The performance of new catalyst types is described, most notably of gold-based catalysts, but also of modified classical Pt, Pd, and Ni catalysts, as well as homogeneous catalysts. The best results for the various chemoselectivity problems are compiled and assessed with regard to their versatility and synthetic viability. In addition, progress in understanding mechanistic aspects are briefly described.

Selective Catalytic Hydrogenation of Functionalized Nitroarenes: An Update

A General Palladium-Catalyzed Coupling of Aryl Bromides/Triflates and Thiols

A novel practical synthesis of benzothiazoles via Pd-catalyzed thiol cross-coupling.

Direct synthesis of hetero-biaryl compounds containing an unprotected NH2 group via Suzuki–Miyaura reaction

A facile bromination of hydroxyheteroarenes

Peptides having the formula ##STR1## inhibit the binding of endothelin to its receptor and are useful in treating diseases associated with excess production or secretion of endothelin.

Toshiaki Mase

Papers

A General Palladium-Catalyzed Coupling of Aryl Bromides/Triflates and Thiols

A novel practical synthesis of benzothiazoles via Pd-catalyzed thiol cross-coupling.

Direct synthesis of hetero-biaryl compounds containing an unprotected NH2 group via Suzuki–Miyaura reaction

A facile bromination of hydroxyheteroarenes

Endothelin antagonistic peptide derivatives