(P

A novel class of (P^N^C) pincer ligands capable of stabilizing elusive gold(III) species is reported here. Straightforward access to (P^N^C)gold(III) hydroxo, formate, and hydride complexes has been streamlined by first incorporating a cycloauration step devoid of toxic metals or harsh conditions. The resulting gold complexes exhibit remarkable stability in solution as well as in the solid state under ambient conditions, which enabled their characterization by X-ray diffraction analyses. Interestingly, the influence of the ligand allowed the preparation of gold(III)-hydrides using mild hydride donors such as H-Bpin, which contrasts with sensitive super hydrides or strong acids and cryogenic conditions employed in previous protocols. A detailed bonding characterization of these species is complemented by reactivity studies.

Low anterior resection with transanal transection and single-stapled anastomosis: technical aspects and initial results.

BACKGROUND: Rectal cancer (RC) is a surgical challenge due to its technical complexity. The double-stapled (DS) technique, a standard for colorectal anastomosis, has been associated with notable drawbacks, including a high incidence of anastomotic leak (AL). Low anterior resection with transanal transection and single-stapled (TTSS) anastomosis has emerged to mitigate those drawbacks. METHODS: Observational study in which it described the technical aspects and results of the initial group of patients with medium-low RC undergoing elective laparoscopic total mesorectal excision (TME) and TTSS. RESULTS: Twenty-two patients were included in the series. Favourable postoperative outcomes with a median length of stay of 5 days and an AL incidence of 9.1%. Importantly, all patients achieved complete mesorectal excision with tumour-free margins, and no mortalities were reported. CONCLUSION: TTSS emerges as a promising alternative for patients with middle and lower rectal tumours, offering potential benefits in terms of morbidity reduction and oncological integrity compared with other techniques.

Asymmetric, Remote C(sp3)-H Arylation via Sulfinyl-Smiles Rearrangement.

An efficient asymmetric remote arylation of C(sp3)-H bonds under photoredox conditions is described here. The reaction features the addition radicals to a double bond followed by a site-selective radical translocation (1,n-hydrogen atom transfer) as well as a stereocontrolled aryl migration via sulfinyl-Smiles rearrangement furnishing a wide range of chiral α-arylated amides with up to >99 : 1 er. Mechanistic studies indicate that the sulfinamide group governs the stereochemistry of the product with the aryl migration being the rate determining step preceded by a kinetically favored 1,n-HAT process.

Dual Nickel/Photoredox-Catalyzed Asymmetric Carbamoylation of Benzylic C(sp3 )-H Bonds.

Radical-mediated Hydrogen Atom Abstraction of Csp3 -H bonds has become a powerful tool for the asymmetric functionalization of organic feedstocks. Here, we present an asymmetric synthesis of α-aryl amides via carbamoylation of alkylarenes with isocyanates as electrophiles. The synergistic combination of a photoredox and a chiral nickel-catalyst, enables the use of readily available and neutral reagents under mild reaction conditions and provides straightforward access to pharmacologically relevant motifs in enantiomerically pure form.

Gold(III) Auracycles featuring C(sp3)-Au-C(sp2) Bonds: Synthesis and Mechanistic Insights into the Cycloauration Step.

The direct auration of arenes is a key step in numerous gold-catalyzed reactions. Although reported more than 100 years ago, understanding of its underlying mechanism has been hampered by the difficulties in the isolation of relevant intermediates given the propensity of gold(III) species to undergo reductive elimination. Here, we report the synthesis and isolation of a new family of intriguing zwitterionic [C(sp3)^C(sp2)]-auracyclopentanes, as well as of their alkyl-gold(III) precursors and demonstrate their value as mechanistic probes to study the Csp2-Au bond-forming event. Experimental investigations employing Kinetic Isotope Effects (KIE), Hammett plot, and Eyring analysis provided important insights into the formation of the auracycle. The data suggest a SEAr mechanism wherein the slowest step might be the p-coordination between the arene and the gold(III) center, en route to the Wheland intermediate. We also show that these auracyclopentanes can work as catalysts in several gold-promoted transformations.

Dual Nickel/Photoredox-Catalyzed Asymmetric Carbosulfonylation of Alkenes.

An asymmetric three-component carbosulfonylation of alkenes is presented here. The reaction, involving the simultaneous formation of a C-C and a C-S bond across the π-system, uses a dual nickel/photoredox catalytic system to produce both ß-aryl and ß-alkenyl sulfones in high yields and with excellent levels of stereocontrol (up to 99:1 er). This protocol exhibits a broad substrate scope and excellent functional group tolerance and its synthetic potential has been demonstrated by successful applications toward pharmacologically relevant molecules. A broad array of control experiments supports the involvement of a secondary alkyl radical intermediate generated through radical addition of a sulfonyl radical to the double bond. Moreover, stoichiometric and cross-over experiments further suggest an underlying Ni(0)/Ni(I)/Ni(III) pathway operative in these transformations.

Nickel-Catalyzed Enantioselective Electrochemical Reductive Cross-Coupling of Aryl Aziridines with Alkenyl Bromides.

An electrochemically driven nickel-catalyzed enantioselective reductive cross-coupling of aryl aziridines with alkenyl bromides has been developed, affording enantioenriched ß-aryl homoallylic amines with excellent E-selectivity. This electroreductive strategy proceeds in the absence of heterogeneous metal reductants and sacrificial anodes by employing constant current electrolysis in an undivided cell with triethylamine as a terminal reductant. The reaction features mild conditions, remarkable stereocontrol, broad substrate scope, and excellent functional group compatibility, which was illustrated by the late-stage functionalization of bioactive molecules. Mechanistic studies indicate that this transformation conforms with a stereoconvergent mechanism in which the aziridine is activated through a nucleophilic halide ring-opening process.

Synthesis of Cyclometalated Gold(III) Complexes via Catalytic Rhodium to Gold(III) Transmetalation.

A catalytic method to synthesize a broad array of cyclometalated (C^N)gold(III) complexes is reported here. An unprecedented Rh-to-AuIII transmetalation allows the facile transfer of (C^N) ligands between these two metals in a redox-neutral process. The reaction employs commercially available precursors and proceeds under mild and environmentally benign conditions. Both experimental and computational studies support a multistep transmetalation from rhodium to gold as the underlying mechanism for these transformations. This process involves first, a rate-determining transfer of the C ligand followed by the subsequent incorporation of the N donor to form the monocyclometalated (C^N)gold(III) species.

Nickel-Catalyzed Asymmetric Synthesis of α-Arylbenzamides.

A nickel-catalyzed asymmetric reductive hydroarylation of vinyl amides to produce enantioenriched α-arylbenzamides is reported. The use of a chiral bisimidazoline (BIm) ligand, in combination with diethoxymethylsilane and aryl halides, enables the regioselective introduction of aryl groups to the internal position of the olefin, forging a new stereogenic center α to the N atom. The use of neutral reagents and mild reaction conditions provides simple access to pharmacologically relevant motifs present in anticancer, SARS-CoV PLpro inhibitors, and KCNQ channel openers.

Synthesis and Characterization of Bidentate (P

A new family of cationic, bidentate (P^N)gold(III) fluoride complexes has been prepared and a detailed characterization of the gold-fluoride bond has been carried out. Our results correlate with the observed reactivity of the fluoro ligand, which undergoes facile exchange with both cyano and acetylene nucleophiles. The resulting (P^N)arylgold(III)C(sp) complexes have enabled the first study of reductive elimination on (P^N)gold(III) systems, which demonstrated that C(sp2 )-C(sp) bond formation occurs at higher rates than those reported for analogous phosphine-based monodentate systems.

Asymmetric Ni-Catalyzed Radical Relayed Reductive Coupling.

Alkene dicarbofunctionalizations enable the streamlined construction of aliphatic structures and have thus been the subject of intense research efforts. Despite significant progress, catalytic asymmetric variants remain scarce. Inspired by the advantages of reductive cross-coupling approaches, we present here a highly efficient asymmetric intermolecular Ni-catalyzed reductive dicarbofunctionalization of alkenes. Two distinct readily available electrophiles, namely, Csp2- and Csp3-halides, are added simultaneously across a variety of olefins (vinyl amides, vinyl boranes, vinyl phosphonates) at room temperature in a highly regio- and enantioselective manner. The reaction, devoid of sensitive organometallic reagents, takes advantage of an in situ generated chiral alkyl Ni(III)-intermediate to ensure a stereodefined outcome in the Csp3-Csp2 bond-forming reaction. An (l)-(+)-isoleucine chiral bisoxazoline ligand and the presence of coordinating sites on the alkene are key for the successful outcome in these "asymmetric radical relayed reductive couplings" (ARRRCs). Further, multiple transformations of the chiral amides obtained in this process showcase the potential of this new methodology for the straightforward assembly of chiral building blocks such as primary and secondary amines and oxazolines, highlighting its synthetic utility.

Phosphorescent κ3 -(N

Efficient OLED devices have been fabricated using organometallic complexes of platinum group metals. Still, the high material cost and low stability represent central challenges for their application in commercial display technologies. Based on its innate stability, gold(III) complexes are emerging as promising candidates for high-performance OLEDs. Here, a series of alkynyl-, N-heterocyclic carbene (NHC)- and aryl-gold(III) complexes stabilized by a κ3 -(N^C^C) template have been prepared and their photophysical properties have been characterized in detail. These compounds exhibit good photoluminescence quantum efficiency (ηPL ) of up to 33 %. The PL emission can be tuned from sky-blue to yellowish green colors by variations on both the ancillary ligands as well as on the pincer template. Further, solution-processable OLED devices based on some of these complexes display remarkable emissive properties (ηCE 46.6 cd.A-1 and ηext 14.0 %), thus showcasing the potential of these motifs for the low-cost fabrication of display and illumination technologies.

Host Abundance and Identity Determine the Epidemiology and Evolution of a Generalist Plant Virus in a Wild Ecosystem.

Increasing evidence indicates that in wild ecosystems plant viruses are important ecological agents, and with potential to jump into crops, but only recently have the diversity and population dynamics of wild plant viruses begun to be explored. Theory proposes that biotic factors (e.g., ecosystem biodiversity, host abundance, and host density) and climatic conditions would determine the epidemiology and evolution of wild plant viruses. However, these predictions seldom have been empirically tested. For 3 years, we analyzed the prevalence and genetic diversity of Potyvirus species in preserved riparian forests of Spain. Results indicated that potyviruses were always present in riparian forests, with a novel generalist potyvirus species provisionally named Iberian hop mosaic virus (IbHMV), explaining the largest fraction of infected plants. Focusing on this potyvirus, we analyzed the biotic and climatic factors affecting virus infection risk and population genetic diversity in its native ecosystem. The main predictors of IbHMV infection risk were host relative abundance and species richness. Virus prevalence and host relative abundance were the major factors determining the genetic diversity and selection pressures in the virus population. These observations support theoretical predictions assigning these ecological factors a key role in parasite epidemiology and evolution. Finally, our phylogenetic analysis indicated that the viral population was genetically structured according to host and location of origin, as expected if speciation is largely sympatric. Thus, this work contributes to characterizing viral diversity and provides novel information on the determinants of plant virus epidemiology and evolution in wild ecosystems.

[C

Pyridine-substituted alkylidenecyclopropanes (Py-ACPs) react with gold(III) salts under mild reaction conditions through an unprecedented, proximal ring-opening pathway, to generate highly appealing, catalytically active pyridine alkenyl [C^N]-gold(III) species. Mechanistic studies reveal that the activation of the C-C bond of the ACP takes place through an unusual concerted, σ-bond metathesis type-process.

Mechanistic Insights into C(sp2 )-C(sp)N Reductive Elimination from Gold(III) Cyanide Complexes.

A new family of phosphine-ligated dicyanoarylgold(III) complexes has been prepared and their reactivity towards reductive elimination has been studied in detail. Both, a highly positive entropy of activation and a primary 12/13 C KIE suggest a late concerted transition state while Hammett analysis and DFT calculations indicate that the process is asynchronous. As a result, a distinct mechanism involving an asynchronous concerted reductive elimination for the overall C(sp2 )-C(sp)N bond forming reaction is characterized herein, for the first time, complementing previous studies reported for C(sp3 )-C(sp3 ), C(sp2 )-C(sp2 ), and C(sp3 )-C(sp2 ) bond formation processes taking place on gold(III) species.

Ni-Catalyzed Reductive Dicarbofunctionalization of Nonactivated Alkenes: Scope and Mechanistic Insights.

Olefins devoid of directing or activating groups have been dicarbofunctionalized here with two electrophilic carbon sources under reductive conditions. Simultaneous formation of one C(sp3)-C(sp3) and one C(sp3)-C(sp2) bond across a variety of unbiased π-systems proceeds with exquisite selectivity by the combination of a Ni catalyst with TDAE as sacrificial reductant. Control experiments and computational studies revealed the feasibility of a radical-based mechanism involving, formally, two interconnected Ni(I)/Ni(III) processes and demonstrated the different ability of Ni(I) species (Ni(I)I vs PhNi(I)) to reduce the C(sp3)-I bond. The role of the reductant was also investigated in depth, suggesting that a one-electron reduction of Ni(II) species to Ni(I) is thermodynamically favored. Further, the preferential activation of alkyl vs aryl halides by ArNi(I) complexes as well as the high affinity of ArNi(II) for secondary over tertiary C-centered radicals explains the lack of undesired homo- and direct coupling products (Ar-Ar, Ar-Alk) in these transformations.

Dual Photoredox/Nickel-Catalyzed Three-Component Carbofunctionalization of Alkenes.

The potential of merging photoredox and nickel catalysis to perform multicomponent alkene difunctionalizations under visible-light irradiation is demonstrated here. Secondary and tertiary alkyl groups, as well as sulfonyl moieties can be added to the terminal position of the double bond with simultaneous arylation of the internal carbon atom in a single step under mild reaction conditions. The process, devoid of stoichiometric additives, benefits from the use of bench-stable and easy-to-handle reagents, is operationally simple, and tolerates a wide variety of functional groups.

κ3 -(N

Gold(III) carboxylate species, stabilized by a κ3 -(N^C^C) ligand template, are presented herein. A η1 -AuIII -C(O)-OH species has been characterized under cryogenic conditions as a result of the nucleophilic attack of an ammonium hydroxide onto a dinuclear µ-CO2 -κ3 -(N^C^C)AuIII precursor. Thermal decomposition for these species proceeds by an unusual decarbonylation process, in contrast to typical decarboxylation pathways observed in related metallocarboxylic acids.

The impact of host genetic diversity on virus evolution and emergence.

Accumulating evidence indicates that biodiversity has an important impact on parasite evolution and emergence. The vast majority of studies in this area have only considered the diversity of species within an environment as an overall measure of biodiversity, overlooking the role of genetic diversity within a particular host species. Although theoretical models propose that host genetic diversity in part shapes that of the infecting parasite population, and hence modulates the risk of parasite emergence, this effect has seldom been tested empirically. Using Rabies virus (RABV) as a model parasite, we provide evidence that greater host genetic diversity increases both parasite genetic diversity and the likelihood of a host being a donor in RABV cross-species transmission events. We conclude that host genetic diversity may be an important determinant of parasite evolution and emergence.

Transforming Olefins into Dinucleophiles.

Herein we present the first example of a three-component dicarbofunctionalization of olefins under reductive conditions. Our strategy takes advantage of nickel catalysis to add aryl and alkyl groups across the double bond with remarkable selectivity. The reaction shows broad functional group compatibility and more importantly, it proves to be general in terms of the alkenes that can be functionalized compared to previous dicarbofunctionalization methods. Initial control experiments reveal different activation modes for both electrophiles and the involvement of alkyl radicals throughout the reaction.