Mathieu Achard

Transition metal catalyzed nucleophilic allylic substitution: activation of allylic alcohols via π-allylic species.

Modern organic synthesis now requires efficient atom economical synthetic methods operating under greener pathways to achieve C-C and C-heteroatom bond formation. Direct activation of allylic alcohols in the presence of transition metal catalysts leading to electrophilic π-allyl metal intermediates represents such a promising target in the field of nucleophilic allylation reactions. During the last decade, this topic of recognized importance has become an emerging area, and selected transition metals, sometimes associated with alcohol activators, have brought elegant solutions for performing allylic substitution directly from alcohols in a regio, stereo and enantioselective manner.

sp3 C-H bond activation with ruthenium(II) catalysts and C(3)-alkylation of cyclic amines.

A selective C(3)-alkylation via activation/functionalization of sp(3) C-H bond of saturated cyclic amines was promoted by (arene)ruthenium(II) complexes featuring a bidentate phosphino-sulfonate ligand upon reaction with aldehydes. This highly regioselective sustainable transformation takes place via initial dehydrogenation of cyclic amines and hydrogen autotransfer processes.

Ruthenium(IV) Complexes Featuring P,O‐Chelating Ligands: Regioselective Substitution Directly from Allylic Alcohols

Branching out: A new ruthenium(IV) complex (1), containing a P,O-chelating ligand, is an efficient precatalyst for regioselective allylations starting from various allylic alcohol derivatives.

Iridium‐Catalyzed Oxidant‐Free Dehydrogenative CH Bond Functionalization: Selective Preparation of N‐Arylpiperidines through Tandem Hydrogen Transfers

In addition to creating efficient and selective methodologies, the rise of green chemistry has led organic chemists and chemical industry to take into account the impact of these processes on the environment. Among the different ecofriendly approaches, homogeneous metal-catalyzed hydrogen autotransfers aimed at developing benign and atom-efficient protocols for the construction of carbon–heteroatom or carbon–carbon bonds have attracted considerable interest. In these reactions, the transient formation of unsaturated carbonyl or imine intermediates, arising from the dehydrogenation of alcohols or amines acting as alkylating reagents, has been successfully used for the preparation of a-alkylated carbonyl derivatives and amines accompanied by the formation of either water or valuable ammonia as the only side product. Owing to the potential of these transformations, recent developments have focused on the preparation of welldefined ruthenium and iridium complexes to allow more selective and milder reaction conditions, water soluble or reusable catalysts, and continuous flow approaches. In addition, the appealing amination from ammonia to afford alkylated amines has been reported by several groups. However, to date no tandem methodologies based on hydrogen autotransfer involving three different partners have been reported. Recently, we achieved the unprecedented oxidant-free dehydrogenation of cyclic N-benzyl and N-alkylamines using a ruthenium(II)–arene catalyst (A ; Scheme 1) featuring a phosphinesulfonate chelate. This reactivity involves hydrogen autotransfers and was successfully applied to the

Ruthenium-catalyzed reductive amination of allylic alcohols.

Straighforward access to various saturated amines from allylic alcohols and isostructural mixture can now be achieved in the presence of arene ruthenium catalyst featuring phosphinesulfonate ligand and a hydrogen donor.

Isoquinoline Derivatives via Stepwise Regioselective sp2 and sp3 C–H Bond Functionalizations

Efficient and practically attractive stepwise ruthenium- and palladium-catalyzed regioselective C-H bond functionalizations were achieved to produce 4-substituted tetrahydroisoquinoline derivatives featuring various heteroaromatic substructures in moderate to good yields. Both ruthenium- and palladium-based catalytic processes generated nontoxic and easily separable side products.

Selective carbon-carbon bond formation: terpenylations of amines involving hydrogen transfers†

The well-defined ruthenium(II) complex A featuring a phosphine sulfonate chelate promotes the introduction of terpene moieties onto cyclic saturated amines through hydrogen “auto” transfers without side alkene reduction. These eco-friendly transformations enable the production of diverse N- and C-terpenoid alkaloids with only water and carbon dioxide as benign side products.

Methyl Ricinoleate as Platform Chemical for Simultaneous Production of Fine Chemicals and Polymer Precursors

The modification of methyl ricinoleate by etherification of the hydroxyl group was accomplished by using a nonclassical ruthenium-catalyzed allylation reaction and also by esterification. Methyl ricinoleate derivatives were engaged in ring-closing metathesis (RCM) reactions leading to biosourced 3,6-dihydropyran and α,β-unsaturated lactone derivatives with concomitant production of polymer precursors. Sequential RCM/hydrogenation and RCM/cross-metathesis were also implemented as a straightforward method for the synthesis of tetrahydropyran and lactone derivatives as well as valuable monomers (i.e., polyamide precursors).

Ruthenium-catalyzed synthesis of functionalized 1,3-dienes.

Functionalized 1,3-diene derivatives have been prepared by regioselective allylation of various nucleophiles with 1,3-dienic carbonates in the presence of a (N,O-carboxylate) allylruthenium precatalyst.

Vicinal α,β‐Functionalizations of Amines: Cyclization Versus Dehydrogenative Hydrolysis

Direct vicinal α,β-difunctionalization of tertiary cyclic amines is achieved in the presence of ruthenium or iridium transition-metal complexes featuring phosphine-sulfonate chelates. By varying the reaction conditions, α-alkylated lactams were obtained by a formal dehydrogenative hydrolysis in which one molecule of hydrogen is generated from water.