Search

Atropisomeric phosphines hold considerable significance in asymmetric catalysis, yet their synthesis presents a formidable challenge owing to intricate multistep procedures. In this context, a groundbreaking methodology has been presented for their preparation. This innovative approach entails an atroposelective rhodium‐catalyzed C−H activation employing aryl and heteroaryl halides, chelated by a P(III) center. The essence of this strategy lies in its ability to directly construct chiral phosphine ligands in a single step, thereby exhibiting exceptional efficiency in terms of atom and redox economy. Illustrative examples serve to demonstrate the immense potential of in situ‐formed ligands in asymmetric catalysis. Mechanistic experiments have further provided invaluable insights into this transformation. [ABSTRACT FROM AUTHOR]

Prized for their ability to generate chemical complexity rapidly, catalytic carbon–hydrogen (C–H) activation and functionalization reactions have enabled a paradigm shift in the standard logic of synthetic chemistry. Directing group strategies have been used extensively in C–H activation reactions to control regio- and enantioselectivity with transition metal catalysts. However, current methods rely heavily on coordination with nitrogen and/or oxygen atoms in molecules and have therefore been found to exhibit limited generality in asymmetric syntheses. Here, we report enantioselective C–H activation with unsaturated hydrocarbons directed by phosphorus centres to rapidly construct libraries of axially chiral phosphines through dynamic kinetic resolution. High reactivity and enantioselectivity are derived from modular assembly of an iridium catalyst with an endogenous phosphorus atom and an exogenous chiral phosphorus ligand, as confirmed by detailed experimental and computational studies. This reaction mode significantly expands the pool of enantiomerically enriched functional phosphines, some of which have shown excellent efficiency for asymmetric catalysis. Directing group strategies have been used extensively in C–H activation reactions but current methods rely heavily on coordination with nitrogen or oxygen atoms in molecules and have therefore been found to exhibit limited generality in asymmetric syntheses. Here, the authors report enantioselective C–H activation with unsaturated hydrocarbons directed by phosphorus centres to rapidly construct libraries of axially chiral phosphines through dynamic kinetic resolution. [ABSTRACT FROM AUTHOR]

Metal‐catalyzed C−H activation strategies provide an efficient approach for synthesis by minimizing atom, step, and redox economy. Developing milder, greener, and more effective protocols for these strategies is always highly desirable to the scientific community. In this study, the utilization of a single rhodium complex enabled the visible‐light‐induced late‐stage C−H activation of biaryl‐type phosphines with alkynyl bromides, employing inherent phosphorus atoms as directing groups. This chemistry combines P(III)‐directed C−H activation with visible light photocatalysis, under exogenous photosensitizer‐free conditions, offering a unique platform for ligand design and preparation. Furthermore, this study also explores the asymmetric catalysis and coordination chemistry of the resulting P‐alkyne hybrid ligands with specific transition metals. Experimental results and density functional theory calculations demonstrate the mechanistic intricacies of this transformation. [ABSTRACT FROM AUTHOR]

Hemilabile ligands have been applied extensively in transition metal catalysis, but preparations of these molecules typically require multistep synthesis. Here, modular assembly of diverse phosphine‐amide ligands, including related axially chiral compounds, is first reported through ruthenium‐catalyzed C−H activation of phosphines with isocyanate directed by phosphorus(III) atoms. High reactivity and regioselectivity can be obtained by using a Ru3(CO)12 catalyst with a mono‐N‐protected amino acid ligand. This transformation significantly expands the pool of phosphine‐amide ligands, some of which have shown excellent efficiency for asymmetric catalysis. More broadly, the discovery constitutes a proof of principle for facile construction of hemilabile ligands directly from the parent monodentate phosphines by C−H activation with ideal atom, step and redox economy. Several dinuclear ruthenium complexes were characterized by single‐crystal X‐ray diffraction analysis revealing the key mechanistic features of this transformation. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Monofluoroalkenes are important and versatile privileged components in pharmacologically relevant molecules. Here, we report a method for the selective construction of these compounds in a diversity‐oriented fashion through regiodivergent cross‐coupling of gem‐difluorocyclopropanes with allylboronates by employing a palladium catalyst with two different ligands, in which gem‐difluorocyclopropanes were used as allyl electrophiles by C—C and C—F bond activation. In the presence of 2‐biphenylyl(diphenyl)phosphine as ligand, the linear‐selective allyl–allyl bond formation is highly obtained, while utilizing the sterically hindered BrettPhos (dicyclohexyl[3,6‐dimethoxy‐2',4',6'‐tris(1‐methylethyl)[1,1'‐biphenyl]‐2‐yl]phosphine) as the ligand favors the generation of the branched‐selective product. Experimental and computational studies investigated the key steps of the cross‐coupling reactions, revealing the origin of the ligand‐controlled regiodivergence. [ABSTRACT FROM AUTHOR]

The widespread use of phosphine ligand libraries is frequently hampered by the challenges associated with their modular preparation. Here, we report a protocol that appends arenes to arylphosphines to access a series of biaryl monophosphines via rhodium-catalyzed P(III)-directed ortho C–H activation, enabling unprecedented one-fold, two-fold, and three-fold direct arylation. Our experimental and theoretical findings reveal a mechanism involving oxidative addition of aryl bromides to the Rh catalyst, further ortho C–H metalation via a four-membered cyclometalated ring. Given the ready availability of substrates, our approach opens the door to developing more general methods for the construction of phosphine ligands. The widespread use of biaryl monophosphines is frequently hampered by the challenges associated with their modular preparation. Here, the authors report a protocol that appends arenes to arylphosphines to access a series of these compounds via rhodium-catalysed P(III)- directed ortho C–H activation, enabling one-fold, two-fold, and threefold direct arylation. [ABSTRACT FROM AUTHOR]

Organophosphines are an important class of ligands widely used in organic chemistry. Although great progress has recently been made in the rapid construction of new phosphines through Rh- or Ru-catalyzed C–H bond functionalizations, synthetic access to more diverse phosphines remains a challenge. We describe an efficient process for the rhodium-catalyzed phosphorus(III)-directed hydroarylation of internal alkynes to generate various alkenylated and 2′,6′-dialkenylated biarylphosphines with high selectivity. A range of diverse alkynes and phosphines were effectively prepared with broad functional-group compatibility under the optimized conditions. In addition, the developed protocol can be extended to modify chiral phosphine ligands, providing enantioenriched alkenylated phosphines without erosion of the enantiomeric excess. [ABSTRACT FROM AUTHOR]

Transition‐metal‐catalyzed C−H borylation has been widely used in the preparation of organoboron compounds. Here, we developed a general protocol on metal‐free P(III)‐directed C−H borylation of phosphines mediated by BBr3, resulting in the formation of products bearing both phosphorus and boron. The development of the metal‐free strategy to mimic previous metallic processes has shown low cost, superior practicality, and environmental friendliness. Density functional theory (DFT) calculations demonstrate the preferred pathway for this metal‐free directed C−H borylation process. [ABSTRACT FROM AUTHOR]

A rhodium‐catalyzed system is introduced for in situ modification of biaryl‐type monophosphines with hydrosilanes through a PIII‐chelation‐assisted dehydrogenative silylation reaction. A series of ligands containing silyl groups with different steric and electronic properties were obtained with excellent regioselectivities. This method offers many advantages, including the use of commercially available phosphines, no requirement for an external ligand or oxidant, a broader substrate scope, high efficiency, and access to a single regioisomer. Based on the outstanding properties of the parent scaffolds, the silyl‐substituted phosphines serve as excellent ligands in Pd‐catalyzed asymmetric Suzuki coupling reactions. [ABSTRACT FROM AUTHOR]

Transition‐metal‐mediated metalation of an aromatic C−H bond that is adjacent to a tertiary phosphine group in arylphosphines via a four‐membered chelate ring was first discovered in 1968. Herein, we overcome a long‐standing problem with the ortho‐C−H activation of arylphosphines in a catalytic fashion. In particular, we developed a rhodium‐catalyzed ortho‐selective C−H borylation of various commercially available arylphosphines with B2pin2 through PIII‐chelation‐assisted C−H activation. This discovery is suggestive of a generic platform that could enable the late‐stage modification of readily accessible arylphosphines. More than a ligand: A rhodium catalytic system has been established for the direct and ortho‐selective borylation of commercially available arylphosphines by PIII‐directed C−H activation. A series of ortho‐boronated phosphines with different steric and electronic properties were obtained in high yields. [ABSTRACT FROM AUTHOR]