Frederic W. Patureau

Pyrrole Synthesis via Allylic sp3 C−H Activation of Enamines Followed by Intermolecular Coupling with Unactivated Alkynes

A conceptually novel pyrrole synthesis is reported, efficiently merging enamines and (unactivated) alkynes under oxidative conditions. In an intermolecular Rh catalyzed process, the challenging allylic sp(3) C-H activation of the enamine substrates is followed by the cyclization with the alkyne (R(3) = CO(2)R). Alternatively, in some cases (R(3) = CN), the enamine can be utilized for a vinylic sp(2) C-H activation. A total of 17 examples with yields above 60% is presented, together with the results of an initial mechanistic investigation.

Rh Catalyzed Olefination and Vinylation of Unactivated Acetanilides

In the catalyzed oxidative olefination of acetanilides (oxidative-Heck coupling), Rh offers great advantages over more common Pd catalysts. Lower catalyst loadings, large functional group tolerance (in particular to halides), and higher reactivity of electron-neutral olefins (styrenes) are some of the attractive features. Most interestingly, even ethylene reacts to yield the corresponding acetanilido-styrene. Moreover, the Cu(II) oxidant can also be utilized in catalytic amounts with air serving as the terminal oxidant.

Diverse Strategies toward Indenol and Fulvene Derivatives: Rh-Catalyzed C−H Activation of Aryl Ketones Followed by Coupling with Internal Alkynes

The synthesis of indenols and fulvenes was achieved through Rh-catalyzed C-H bond activation of simple and diverse aryl ketone derivatives and subsequent coupling with internal alkynes. The process was found to involve either an α or γ dehydration step, depending on the substrate disposition and representing diverse pathways toward functionalized fulvenes.

Singly hydrogen bonded supramolecular ligands for highly selective rhodium-catalyzed hydrogenation reactions

H bonds make the catalysts! A single hydrogen bond between ligands coordinated to a rhodium center is critical for the formation of pure supramolecular catalysts for asymmetric hydrogenation reactions. The ester group of the amidite ligand (see scheme) also forms a hydrogen bond with the coordinated substrate. Use of the heterocomplex afforded the highest enantioselectivity reported to date for the hydrogenation of several ester substrates.

Rh Catalyzed C–H Activation and Oxidative Olefination without Chelate Assistance: On the Reactivity of Bromoarenes

A Rh catalyzed, no-chelate-assisted C-H activation/oxidative olefination reaction of bromoarenes has been discovered, in which the latter ones seem to act as a substrate, terminal oxidant, and catalyst modifier.

Base-Free Production of H2 by Dehydrogenation of Formic Acid Using An Iridium–bisMETAMORPhos Complex

Erase the base: An iridium complex based on a cooperative ligand that functions as an internal base is reported. This complex can rapidly and cleanly dehydrogenate formic acid in absence of external base, a reaction that is required if formic acid is to be exploited as an energy carrier (see scheme).

Toward Polynuclear Ru–Cu Catalytic Dehydrogenative C–N Bond Formation, on the Reactivity of Carbazoles

The cooperative action of Ru and Cu catalysts enables direct polynuclear C-H and N-H activation for the dehydrogenative N-carbazolation of carbazoles, selectively at the C1 position. Initial mechanistic experiments are presented and discussed.

Ruthenium-Catalyzed Cross-Dehydrogenative ortho-N-Carbazolation of Diarylamines: Versatile Access to Unsymmetrical Diamines†

The dehydrogenative C-N cross-coupling of unprotected, secondary anilines through ortho-N-carbazolation has been achieved using a Ru catalytic system with O2 as the terminal oxidant. The reactions proceed in an intermolecular fashion, selectively in the ortho position. Implications for the field of organic synthesis are discussed.

O2‐mediated dehydrogenative amination of phenols

A method was developed for the direct dehydrogenative construction of CN bonds between unprotected phenols and a series of cyclic anilines without resorting to any kind of metal activation of either substrate and without the use of halides. The resulting process relies on the exclusively organic activation of molecular oxygen and the subsequent oxidation of the aniline substrate. This allows the coupling of ubiquitous phenols, thus furnishing aminophenols through an atom-economical and most sustainable dehydrogenative amination method. This new reactivity, which relies on the intrinsic organic reactivity of cumene in what can be seen as a modified Hock activation process of oxygen, is expected to have a large impact on the formation of CN bonds in organic synthesis.

Rh(III)- and Ir(III)-Catalyzed C–C Bond Cross Couplings from C–H Bonds

Over the recent years, dicationic [Cp*Ir(III)] and more particularly [Cp*Rh(III)] complexes have established themselves as extremely powerful catalysts enabling direct C–H activation of various aromatic and vinylic compounds. During such transformations, a common metallacyclic intermediate [Cp*M(C^X)] (M=Ir, Rh) is formed and undergoes further transformations, according to the nature of the coupling partner, to finally afford a myriad of valuable, often complex, and otherwise difficult to access scaffolds like heterocycles and polyunsaturated skeletons. The major advances achieved in this field clearly showcase the potential of these catalysts to functionalize latent C–H bonds under surprisingly mild reaction conditions. The aim of this chapter is to present the latest and most representative contributions in the field of Rh(III)- and Ir(III)-catalyzed C–H activation by focusing on the reactivity of the corresponding metallacyclic intermediates.