A catalytic transfer-hydrogenation utilizing a well-defined Bi(I) complex as catalyst and ammonia-borane transfer agent has been developed. This transformation represents unique example of low-valent pnictogen catalysis cycling between oxidation states I III, proved useful for the hydrogenation azoarenes partial reduction nitroarenes. Interestingly, bismuthinidene performs well in presence transition-metal sensitive functional groups presents orthogonal reactivity compared to analogous...

Teaching bismuth to make and break bonds One major reason why transition metals are good catalysts is that they can shuttle between oxidation states. This flexibility lets them slide in out of chemical bonds; so, for instance, snip a bond carbon boron then stitch carbonfluorine its place. Planas et al. now report also orchestrate such bond-swapping events. They implement fully catalytic cycle fluorination aryl boronates, which hops +3 +5 Science , this issue p. 313

Abstract The development of new CH functionalization protocols based on inexpensive cobalt catalysts is currently attracting significant interest. Functionalized 8‐aminoquinoline compounds are high‐potential building blocks in organic chemistry and pharmaceutical facile routes for their preparation would be highly valuable. Recently, copper has been applied as catalyst the found to operate through a single electron transfer (SET) mechanism, although requiring elevated reaction temperatures....

Herein we present a Bi-catalyzed cross-coupling of arylboronic acids with perfluoroalkyl sulfonate salts based on Bi(III)/Bi(V) redox cycle. An electron-deficient sulfone ligand proved to be key for the successful implementation this protocol, which allows unusual construction C(sp2)–O bonds using commercially available NaOTf and KONf as coupling partners. Preliminary mechanistic studies well theoretical investigations reveal intermediacy highly electrophilic Bi(V) species, rapidly...

Abstract The use of cobalt as catalyst in direct CH activation protocols a replacement for more expensive second row transition metals is currently attracting significant attention. Herein we disclose facile cobalt‐catalyzed functionalization route towards sultam motifs through annulation easily prepared aryl sulfonamides and alkynes using 8‐aminoquinoline directing group. reaction shows broad substrate scope with products obtained highly regioselective manner good to excellent isolated...

The selective annulation reaction of alkynes with substrates containing inert C-H bonds using cobalt as catalyst is currently a topic attracting significant interest. Unfortunately, the mechanism this transformation still relatively poorly understood, little experimental evidence for intermediates, although an organometallic Co(III) species generally implicated. Herein, we describe rare example preparation and characterization benchtop-stable aryl-Co(III) compounds (NMR, HRMS, XAS, XRD)...

In this article, we describe a combined experimental and theoretical mechanistic investigation of the C(sp

A structural synthetic model of the iron(IV)-oxo-halide active species non-heme iron dependent halogenases is reported. Compounds with general formula [Fe(IV)(O)(X)(Pytacn)](+) (1-X, X = Cl, Br) have been prepared and characterized spectroscopically chemically regard to their oxidizing ability. 1-X performs hydrogen-atom abstraction C-H bonds at reaction rates 2-3 times faster than corresponding solvato dicationic species, thus modelling first step in functionalization taking place natural...

Herein we describe a new class of zwitterionic heavier pnictogen species with bis(NHC)borate as stabilizing ligands, enabling the isolation Sb and Bi in +1, +2, +3 oxidation states. Computational analysis pnictinidines revealed their cationis character, well unique electronic properties that contribute to nucleophilicity stability. These systems participate key organometallic transformations, including oxidative addition reductive elimination pro-cesses, display redox catalytic activity...

Reported herein are organometallic Ni(<sc>ii</sc>) complexes that react with mild oxidants such as O₂ and H₂O₂ exhibit oxidatively-induced reactivity to yield C–C C–O bond formation products <italic>via</italic> observable high-valent Ni intermediates.

Organobismuth-catalyzed transfer hydrogenation has recently been disclosed as an example of low-valent Bi redox catalysis. However, its mechanistic details have remained speculative. Herein, we report experimental and computational studies that provide insights into a Bi-catalyzed azoarenes using p-trifluoromethylphenol (4) pinacolborane (5) hydrogen sources. A kinetic analysis elucidated the rate orders in all components catalytic reaction determined 1...

Herein we describe the synthesis of a family aryl-Co(III)-carboxylate complexes and their reactivity with ethyl diazoacetate. Crystallographic, full spectroscopic characterization, theoretical evidence unique C-metalated aryl-Co(III) enolate intermediates is provided, unraveling carboxylate-assisted formation masked-carbenes. Moreover, additional for an unprecedented Co(III)-mediated intramolecular SN2-type C-C bond in which carboxylate moiety acts as relay disclosed. This novel strategy key...

Electronic and steric parameters influencing the stability reactivity of aryl-Co(<sc>iii</sc>) masked carbenes have been evaluated.

Herein we explore the intrinsic organometallic reactivity of iron embedded in a tetradentate N3C macrocyclic ligand scaffold that allows stabilization aryl-Fe species, which are key intermediates Fe-catalyzed cross-coupling and C-H functionalization processes. This study covers activation reactions using MeLH FeCl2, biaryl C-C coupling product formation through reaction with Grignard reagents, MeLBr or HLBr combination Fe0(CO)5. Synthesis under light irradiation moderate heating (50 °C)...

Cobalt-catalyzed C-H amination via M-nitrenoid species is spiking the interest of research community. Understanding this process at a molecular level challenging task, and here we report well-defined macrocyclic system featuring pseudo-Oh aryl-CoIII that reacts with aliphatic azides to effect intramolecular Csp2-N bond formation. Strikingly, putative aryl-Co═NR nitrenoid intermediate formed rapidly trapped by carboxylate ligand form masked-nitrene, which functions as shortcut stabilize guide...

Abstract In the last years, bismuth has transitioned from being considered a mere Lewis acid catalyst to recognised as an interesting redox for organic synthesis. A rational design of ligand scaffold Bi center resulted in robust catalytic system applicable various processes.

Abstract Organobismuth‐catalyzed transfer hydrogenation has recently been disclosed as an example of low‐valent Bi redox catalysis. However, its mechanistic details have remained speculative. Herein, we report experimental and computational studies that provide insights into a Bi‐catalyzed azoarenes using p ‐trifluoromethylphenol ( 4 ) pinacolborane 5 hydrogen sources. A kinetic analysis elucidated the rate orders in all components catalytic reaction determined 1 (2,6‐bis[ N‐ tert...

Previously, an unexpected Co-catalysed remote C-H nitration of 8-aminoquinolinamide compounds was developed. This report provided a novel reactivity for Co which assumed to proceed through the mechanistic pathway already known analogous Cu-catalysed couplings same substrates. In order shed light into this intriguing, and previously unobserved Co, thorough computational study has now been performed, allowed full understanding operative mechanism. demonstrates that coupling does not occur...

Abstract A novel Co‐catalyzed remote nitration protocol for the preparation of 5‐ and 7‐nitro‐8‐aminoquinolines using installable removable ancillary groups is described.