Julien Roger

University of Burgundy | UB · Institut de Chimie Moléculaire de l'Université de Bourgogne (ICMUB)

The direct palladium‐catalyzed C−H arylation of 1,3,4‐oxadiazoles with challenging aryl chloride substrates is promoted by the use of a specifically designed electron‐rich ferrocenyl diphosphane. This protocol employs 0.5 to 1.0 mol % catalyst loading without any additives such as copper or ammonium salts, and equally tolerates electron‐donating an...

The synthetic scope of 3-arylated tetrazo[1,2-b]indazoles is reported based on a Pd-catalyzed Liebeskind-Srogl cross-coupling reaction followed by an N-cyclisation process. The reactivity of the nitrogen atoms was used to further diversify these N-rich polyaromatic tetrazo[1,2-b]indazoles in a panel of reactions (protonation, selective oxidation, m...

The straightforward access to a new class of aza‐polyaromatics is reported. Starting from readily available fluorinated s‐tetrazine, a cyclization process with azide leads to the formation of an unprecedented tetrazo[1,2‐b]indazole or a bis‐tetrazo[1,2‐b]indazole (cis and trans conformers). Based on the new nitrogen core, further N‐directed palladi...

The straightforward access to a new class of aza‐polyaromatics is reported. Starting from readily available fluorinated s‐tetrazine, a cyclization process with azide leads to the formation of an unprecedented tetrazo[1,2‐b]indazole or a bis‐tetrazo[1,2‐b]indazole (cis and trans). Based on the new nitrogen core, further N‐directed palladium‐catalyze...

Aryl triflates were selected as suitable electrophile coupling partners for the P-directed rhodium(III) catalyzed direct C–H arylation of polyaromatic phosphines. We report herein simple conditions in the peri-C–H functionalization of polyarylphosphines, where the [Rh(III)Cl2Cp*]2 precatalyst is employed to provide a convenient access to polyarylat...

We describe the synthesis and characterization of two classes of hybrid phosphino ligands functionalized with amino ester or amino acid groups. These compounds are built either on a rigid planar phenyl platform or on a functionalized – conformationally controlled – rotational ferrocene backbone. Modifications at the −PR2 phosphino groups (R=aryl an...

A general palladium-catalysed selective C-H halogenation reaction is reported, which was successfully achieved for a large variety of functionalized aromatic rings incorporating diverse N-directing groups. By using simple alkali halides of MX type as the nucleophilic reagent source (M = Li, Na, K, Cs and X = I, Br and Cl), and phenyliodanediacetate...

In comparison to mononuclear gold Lewis acid catalysts, digold complexes and dual‐gold catalysis have illustrated a distinct and powerful potential for the activation of carbon‐carbon multiple bonds. Herein, this concept is pushed further by designing novel tetranuclear gold(I) dicationic complexes structurally supported by strongly stabilizing con...

C−H arylation of 1‐pyrenylphosphine derivatives catalyzed by rhodium and directed by a diphenylphosphino group is selectively achieved at the K‐region, i. e. 4‐, 5‐, 9‐, or 10‐position of the pyrene moiety. This peri C−H activation/arylation of pyrenes using (hetero)aryl bromide coupling partners tolerates both electron‐donating and electron‐withdr...

Dihydrogen is one of the sustainable energy vectors envisioned for the future. However, the rapidly reversible and secure storage of large quantities of hydrogen is still a technological and scientific challenge. In this context, this review proposes a recent state‐of‐the‐art on H2 production capacities from the dehydrogenation reaction of ammonia...

The carbon-carbon cross-coupling of phenyl s-tetrazine (Tz) units at their ortho-phenyl positions allows the formation of constrained bis(tetrazines) with original tweezer structures. In these compounds, the face-to-face positioning of the central tetrazine cores is reinforced by π-stacking of the electron-poor nitrogen-containing heteroaromatic mo...

The carbon-carbon cross-coupling of phenyl s-tetrazine (Tz) units at their ortho-phenyl positions allows to form constrained bis(tetrazines) with original tweezer structures. In these compounds, the face-to-face positioning of the central tetrazine cores is endorsed by pi-staking of the electron-poor nitrogen-containing heteroaromatic moieties. The...

Direct arylation of most five‐membered ring heterocycles are generally easily accessible and strongly favored at the α‐position using classical palladium‐catalysis. Conversely, regioselective functionalization of such heterocycles at the concurrent β‐position remains currently very challenging. Herein, we report general conditions for regioselectiv...

Ultrasmall gold nanoparticles (NPs) stabilized in networks by polymantane ligands (diamondoids) were successfully used as precatalysts for highly selective heterogeneous gold-catalyzed dimethyl allyl(propargyl)malonate cyclization to 5-membered conjugated diene. Such reaction usually suffers from selectivity issues with homogeneous catalysts. This...

An expedient two-steps synthesis produces in good yield polyaromatic heptacyclic (hetero)arylated o-substituted s-aryltetrazines (s-Tz) directly from diphenyl s-tetrazine. This methodology overcomes the steric limitations of classical Pinner-like syntheses encountered for o-functionalized s-Tz. A single step palladium-catalyzed N-directed C–H bond...

Combined experiments and modelling rationalize the large influence of solvent composition on pyrrolidine nucleophilicity.

Di‐tert‐butylated‐bis(phosphino)ferrocene ligands bearing phosphino substituents R (R=phenyl, cyclohexyl, iso‐propyl, mesityl, or furyl) allow tuning the selective formation of Au(I) halide complexes. Thus, dinuclear linear two‐coordinate, but also rare mononuclear trigonal three‐coordinate and tetrahedral four‐coordinate complexes were formed upon...

The kinetics of the reactions of 4‐nitrobenzofurazane 1a , 4‐nitrobenzothiadiazole 1b , and 4‐nitrobenzoselenadiazole 1c with a series of 4‐Y‐substituted phenoxide anions 2a‐e (Y = OMe, Me, H, Cl, and CN) in aqueous solution at 20°C were investigated photometrically. The derived second‐order rate constants (k 2) have been combined with the nucleoph...

Porphyrins provide an extremely flexible synthetic scaffold for numerous applications such as artificial photosynthesis, photodynamic therapy, molecular recognition, oxidation/reduction catalysts and molecular materials. [1] The fusion of one or several hydrocarbon(s) or aromatic heterocycle(s) onto the porphyrin periphery forces the porphyrin core...

In this work, new receptors built on the porphyrin scaffold were synthesized for halophenols recognition. A quinolyl group was introduced on the porphyrin's periphery as binding site, to form two series of molecules based on two distinct porphyrin frames and which were obtained in free base and zinc forms. The binding between these porphyrin‐based...

Ferrocene is unique among organometallic compounds, and serves notably as a versatile platform towards the production of ligands useful to promote transition metals chemistry. A general limiting aspect of the synthesis of ferrocene derivatives is the efficient access to sophisticated highly functionalized polysubstituted ferrocenes, i.e. bearing fo...

Four free base aminoporphyrins were synthesized in two steps via regioselective anodic nucleophilic substitution with pyridine followed by ring opening of the electrogenerated pyridinium with piperidine. The X-ray crystallographic structure of the unstable 2-aminotetraphenylporphyrin was solved. Protonation of this latter compound leads to the stab...

Click chemistry at a tetrazine core is useful for bioorthogonal labeling and crosslinking. Introduced here are two new classes of doubly clickable s‐aryl tetrazines synthesized by Cu‐catalyzed cross‐coupling. Homocoupling of o‐brominated s‐aryl tetrazines leads to bis(tetrazine)s structurally characterized by tetrazine cores arranged face‐to‐face....

Palladium-catalyzed oxidative C–H halogenation and acetoxylation reactions of S-unprotected sulfides, selectively directed by pyridinyl groups, allows the formation of C–X bonds (X = I, Br, Cl, OAc) by using simple halosuccinimide or phenyliodine diacetate (PIDA) oxidants. The undesired formation of sulfoxides and/or sulfones, which are usually obs...

Tetrazine core “click‐chemistry” is a blooming method for bioorthogonal labeling and crosslinking. We introduce two new classes of doubly clickable s‐aryl tetrazines synthesized by Cu‐catalyzed cross‐coupling. Homocoupling arylation applied to o‐brominated s‐aryl tetrazines leads to bis‐tetrazines structurally‐characterized by tetrazine cores arran...

A new class of tritopic ferrocene-based ambiphilic compound has been prepared by assembling diphosphino- and boryl-substituted cyclopentadienides at iron. The presence of five sterically demanding substituents on the ferrocene platform...

Metal-catalysed ortho-directed C–H functionalization usually faces selectivity issues in competition between mono- and disubstitued processes. We report the ruthenium-catalysed N-directed C–H monoarylation of arylpyrazoles with a selectivity up to 96...

A general challenging issue in the synthesis of hemilabile ferrocene ligands is the access to highly functionalized ferrocene starting materials. These can bear donor/acceptor atoms, additional functional and structuring spectator substituents, but the preparation of such species poses general synthetic difficulties. We report herein alternative sy...

The Cover Feature shows the “Vitruvian Man”, a drawing made by the universal genius Leonardo da Vinci around 1490. For more than five centuries the mysteries carried out by this picture have been discussed in mathematics, arts, alchemy, and philosophy. At the dawn of amazing chemical direct modifications of C–H bonds, the last decade has also seen...

Palladium‐catalyzed electrophilic fluorination is a particularly attractive and challenging synthetic issue. Because of the rapid evolution of this topic, a critical point on the mechanistic and experimental advances is provided herein. In the present review, we focused on current mechanistic understanding in electrophilic fluorination (and related...

Aryl triflates and related phenolates are suitable electrophile coupling partners for the ruthenium‐catalyzed direct arylation of heteroaromatic substrates using azole N‐directed Csp²–H activation. We report herein convenient conditions for the efficient ortho‐C–H functionalization of aryl‐pyrazoles, thiazoles and pyridines in which [RuCl2(p‐Cym)]2...

The mild (electro)chemical oxidation of pyridin-2-ylthio-meso substituted Ni(II) porphyrins affords C-N fused cationic and dicationic pyridinium-based derivatives. These porphyrins are fully characterized and the molecular structure of one of them...

We provide efficient synthetic access to heteroaryl sulfones in two-steps using a simple palladium–1,1′-bis[(diphenyl)phosphanyl)]ferrocene catalyst to form in high yields highly functionalized heteroaromatic thioethers. Pyridinyl-containing substrates can be subsequently selectively oxidized into sulfones and NH-sulfoximines by using very mild oxi...

We report a general route for synthesizing ortho-substituted unsymmetrical biphenyl and polyaromatic s-aryltetrazines. These compounds are inaccessible by classical Pinner hydrazine condensation or by the current s-aryltetrazine aromatic core functionalization methods described up to now. We exploited multiple versatile N-directed palladium C–H act...

We report a general route for synthesizing ortho-substituted unsymmetrical biphenyl and polyaromatic s-aryltetrazines. These compounds are inaccessible by classical Pinner hydrazine condensation or by the current s-aryltetrazine aromatic core functionalization methods described up to now. We exploited multiple versatile N-directed palladium C–H act...

We describe an efficient palladium‐catalyzed selective C–H ortho ‐monohalogenation (X=I, Br, Cl, F) of various functionalized (2‐pyridyl)arylsulfones. ortho‐ , meta‐ and para ‐functionalization is tolerated at the arene group which undergoes C–H halogenation. Some modifications are also possible on the 2‐(arylsulfonyl)heteroaryl directing groups. A...

Unequally functionalized ferrocenes give access to valuable hemilabile reactivity in catalytic reaction. We address the synthesis of hybrid (P, N)-ferrocenyl compounds for which recent catalytic breakthrough applications have been reported, transversely in late transition metals chemistry. Palladium, nickel, rhodium, iridium, and emerging iron and...

A general synthesis of highly functionalized ferrocenes, which includes (P, B)- and (N, B)-ambiphiles has been developed at multigram scale. Diastereoselective stepwise modification of di-tert-butylated ferrocene included the unprecedented separation of electroactive species. Bulky alkyl groups on ferrocene insure planar chirality of ambiphiles and...

A method that allows hindered ortho-substituted aryl iodides to be efficiently coupled to phenylboronic acid using a gold-catalyzed C-C bond formation is presented. The use of a molecularly-defined dinuclear gold chloride catalytic precursor that is stabilized by a new tetradentate (N,N')-diamino-(P,P')-diphosphino ferrocene hybrid ligand in a Suzu...

A smart steric control of the metallocene backbone in bis- and poly(phosphino)ferrocene ligands favors intramolecular aurophilic interactions between [AuCl] fragments in polynuclear gold(I) complexes. We synthesized and characterized by multinuclear NMR and X-ray diffraction analysis mono-, di-, and polynuclear gold complexes of constrained ferroce...

The direct arylation of substituted pyrroles and imidazoles is presented.

Reaction conditions are developed for ortho-selective Pd-catalyzed C—H functionalization of biphenyl-1,2,4,5-tetrazine.

The diastereoselective synthesis of dialkylated ferrocenyl bis(phosphane)s bearing aryl, alkyl, and hetero- or polycyclic substituents on the phosphino groups is reported, together with their characterization in the solid state by X-ray structure analysis and in solution by multinuclear NMR spectroscopy. Introduction of various alkyl groups on the...

A general catalyzed direct C-H functionalization of s-tetrazines is reported. Under mild reaction conditions, N-directed ortho-C-H activation of tetrazines allows the introduction of various functional groups, thus forming carbon-heteroatom bonds: C-X (X=I, Br, Cl) and C-O. Based on this methodology, we developed electrophilic mono- and poly-ortho-...

Palladium–polypyrrole nanocomposites (Pd@PPy) with unique combination of high palladium dispersion (nanoparticle size 2.4 nm) and high palladium content (35 wt%) are efficient catalysts for the selective arylation of substituted pyrroles and imidazoles with either activated or deactivated aryl bromides. The performances of the recoverable supported...

The present invention relates to a process for the synthesis of 3,6 functionalized 1,2,4,5-tetrazine compounds of general formula (I). 5 (I) as defined thereafter. The chemistry of s-tetrazines (1,2,4,5-tetrazines) has attracted increasing interest over the years, owing to multiple applications (biochemical, materials) in relation with their unique...

Hexasubstituted hybrid tetradentate (N,N',P,P')-ferrocenes bearing phosphino and aminomethyl groups, plus hindering tert-butyl moieties, were synthesized by using two different strategies: a "diverging" synthesis involving successive functionalization of preformed di-tert-butylated ferrocene and a "converging" assembly of the species from appropria...

A general protocol for palladium‐catalysed CH mono‐ and di‐fluorination of highly substituted arylpyrazoles is reported. Coupling pathways and substrate limitations are discussed in the light of complementary mechanistic experimental and density functional theory (DFT) studies. The mono‐ and di‐ ortho ‐fluorination of arylpyrazoles having substitu...

A general alkylation of heterocycles using a simple palladium catalyst is reported. Most classes of heterocycles, including indoles and pyridines, efficiently coupled with unactivated secondary and tertiary alkyl halides. An alkyl radical addition to neutral heteroarenes is most likely involved.

A general alkylation of heterocycles using a simple palladium catalyst is reported. Most classes of heterocycles, including indoles and pyridines, efficiently coupled with unactivated secondary and tertiary alkyl halides. An alkyl radical addition to neutral heteroarenes is most likely involved.

The arylation of aniline derivatives with dichloroarenes under a low palladium content (below the currently used 5 to 10 mol%) was studied using nine different ferrocenylphosphine ligands, including the easily accessible 1,1'-bis(diphenylphosphino) ferrocene, DPPF. The electron-enriched air-stable tridentate ferrocenylpolyphosphine 1,2-bis(diphenyl...

Unsym.- substituted controlled conformation ferrocenes 1, 1'- R12- 3- R2- 3'- R3- (η5- C5H3) 2Fe (1; R1 = bulky group, preferably, trialkylmethyl, tBu, iPr, iBu; R2 = electron- donating group, Lewis base, phosphino; R3 = electron- accepting group, Lewis acid, such as boryl, borono, trifluoroborato) , useful as ligands for transition metal- catalyze...

A variety of aminomethyl-substituted ferrocenes and the parent compounds (iminomethyl)ferrocenes, azaferrocenophanes, and diferrocenylamines can be selectively synthesized from reductive amination of 1,1′-diformylferrocene or formylferrocene. The optimized one- or two-step reactions have delivered 13 new compounds, isolated in 65–97% yields, which...

A novel and efficient palladium-catalysed direct di-heteroarylation of 1,2-dichloroperfluorocyclopentene with a variety of heteroarenes is reported, giving rise to 1,2-di(heteroaryl)ylperfluorocyclopentene photochromic compounds. The reaction proceeds with thiazoles, thiophenes or furan derivatives and tolerates various substituents.

The palladium-catalyzed direct arylation at C2 or C5 of free NH2 substituted thiophene derivatives was found to proceed in moderate to high yields using a variety of aryl halides. The choice of potassium acetate as the base was found to be crucial to inhibit the amination reaction and to promote the direct arylation.