Palladium-catalyzed amination reactions of aryl halides have undergone rapid development in the last 12 years, largely driven by the implementation of new classes of ligands. Biaryl phosphanes have proven to provide especially active catalysts in this context. This Review discusses the application of these catalysts in C-N cross-coupling reactions in the synthesis of heterocycles and pharmaceuticals, in materials science, and in natural product synthesis.

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Biaryl Phosphane Ligands in Palladium‐Catalyzed Amination

Pd-catalyzed cross-coupling reactions that form C–N bonds have become useful methods to synthesize anilines and aniline derivatives, an important class of compounds throughout chemical research. A key factor in the widespread adoption of these methods has been the continued development of reliable and versatile catalysts that function under operationally simple, user-friendly conditions. This review provides an overview of Pd-catalyzed N-arylation reactions found in both basic and applied chemical research from 2008 to the present. Selected examples of C–N cross-coupling reactions between nine classes of nitrogen-based coupling partners and (pseudo)aryl halides are described for the synthesis of heterocycles, medicinally relevant compounds, natural products, organic materials, and catalysts.

Applications of Palladium-Catalyzed C–N Cross-Coupling Reactions

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

Alan Ford,† Hugues Miel, Aoife Ring,† Catherine N. Slattery,† Anita R. Maguire,*,†,‡ and M. Anthony McKervey* †Department of Chemistry and ‡School of Pharmacy, Analytical and Biological Chemistry Research Facility, Synthesis and Solid State Pharmaceutical Centre, University College Cork, Cork, Ireland Almac Discovery Ltd., David Keir Building, Stranmillis Road, Belfast BT9 5AG, United Kingdom Almac Sciences Ltd., Almac House, 20 Seagoe Industrial Estate, Craigavon BT63 5QD, United Kingdom

Modern Organic Synthesis with α-Diazocarbonyl Compounds

In this (tutorial overview) perspective we highlight the use of “redox non-innocent” ligands in catalysis. Two main types of reactivity in which the redox non-innocent ligand is involved can be specified: (A) The redox active ligand participates in the catalytic cycle only by accepting/donating electrons, and (B) the ligand actively participates in the formation/breaking of substrate covalent bonds. On the basis of these two types of behavior, four main application strategies of redox-active ligands in catalysis can be distinguished: The first strategy (I) involves oxidation/reduction of the ligand to tune the electronic properties (i.e., Lewis acidity/basicity) of the metal. In the second approach (II) the ligand is used as an electron reservoir. This allows multiple-electron transformations for metal complexes that are reluctant to such transformations otherwise (e.g., because the metal would need to accommodate an uncommon, high-energy oxidation state). This includes examples of (first row) transition ...

Redox Non-Innocent Ligands: Versatile New Tools to Control Catalytic Reactions

5,10-Bis(2‘,6‘-dibromophenyl)porphyrins bearing various substituents at the 10 and 20 positions were demonstrated to be versatile synthons for modular construction of chiral porphyrins via palladium-catalyzed amidation reactions with chiral amides. The quadruple carbon−nitrogen bond formation reactions were accomplished in high yields with different chiral amide building blocks under mild conditions, forming a family of D2-symmetric chiral porphyrins. Cobalt(II) complexes of these chiral porphyrins were prepared in high yields and shown to be active catalysts for highly enantioselective and diastereoselective cyclopropanation under a practical one-pot protocol (alkenes as limiting reagents and no slow addition of diazo reagents).

Bromoporphyrins as versatile synthons for modular construction of chiral porphyrins: Cobalt-catalyzed highly enantioselective and diastereoselective cyclopropanation

A Highly Effective Cobalt Catalyst for Olefin Aziridination with Azides: Hydrogen Bonding Guided Catalyst Design

Cobalt(II) porphyrin complexes were shown to be general and efficient catalysts for selective cyclopropanation of alkenes with ethyl diazoacetate (EDA). The catalytic system can operate with alkenes as limiting reagents, requiring only stoichiometric amounts of EDA. The protocol is performed in one-pot fashion without the need of slow addition of EDA. The diastereoselectivity of the current system can be tuned by using different porphyrin ligands or additives, giving either trans- or cis-dominant cyclopropanes. The asymmetric cyclopropanation was also demonstrated with the use of chiral cobalt porphyrin complexes.

Diastereoselective and enantioselective cyclopropanation of alkenes catalyzed by cobalt porphyrins.

The cobalt(II) complex of D2-symmetric chiral porphyrin [Co(1)] is an effective catalyst for highly diastereoselective and enantioselective cyclopropanation of a broad range of styrene derivatives under mild conditions. Dimerization of diazo compounds, a common side reaction in metal-mediated carbene transfer processes, is minimized in a cobalt porphyrin-based system, obviating the need to employ excess substrates and slow addition of diazo compounds. The high catalytic activity and selectivity of [Co(1)] evidently resulted from the appropriate combination of the cobalt ion and the chiral porphyrin 1 as the use of iron(III) complex of the same ligand [Fe(1)Cl] afforded the desired cyclopropane products in low yields and poor enantioselectivity.

Asymmetric cyclopropanation of styrenes catalyzed by metal complexes of D2-symmetrical chiral porphyrin: superiority of cobalt over iron.

The commercially available Fe(III) and Ru(II) porphyrin complexes Fe(TPP)Cl and Ru(TPP)(CO) are efficient catalysts for selective olefination of a variety of aldehydes with ethyl diazoacetate in the presence of triphenylphosphine. The reactions were carried out under mild conditions in a one-pot fashion with the use of a stoichiometrical amount of EDA, which proceeded with excellent yields and high (E)-selectivity. Air atmosphere, low catalyst loadings, and functional group tolerance were also demonstrated.

Ying Chen

Papers

Bromoporphyrins as versatile synthons for modular construction of chiral porphyrins: Cobalt-catalyzed highly enantioselective and diastereoselective cyclopropanation

A Highly Effective Cobalt Catalyst for Olefin Aziridination with Azides: Hydrogen Bonding Guided Catalyst Design

Diastereoselective and enantioselective cyclopropanation of alkenes catalyzed by cobalt porphyrins.

Asymmetric cyclopropanation of styrenes catalyzed by metal complexes of D2-symmetrical chiral porphyrin: superiority of cobalt over iron.

Iron(III) and ruthenium(II) porphyrin complex-catalyzed selective olefination of aldehydes with ethyl diazoacetate.