C–C Bond Formation on Activation of Alkynes and Alkenes with (C5R5)Ru Catalysts

International audienceElectron-rich ruthenium(II) catalysts of type (C5R5)XRuL n are used to perform selective carbon–carbon bond formation by combination of simple substrates such as the coupling of functional alkynes and alkenes with a variety of unsaturated molecules (alkynes, diynes, alkenes, dienes) or non-unsaturated molecules such as alcohols or water, often with atom economy. Various selective transformations are developed and can provide access to high multifunctional molecules. These reactions often proceed via an initial oxidative coupling leading to a ruthenacycle intermediat

One-step synthesis of 1-halo-1,3-butadienes via ruthenium-catalysed hydrohalogenative dimerisation of alkynes.

International audienceAn efficient, novel and direct access to 1-halo-1,3-butadienes is developed. This stereoselective ruthenium-catalysed reaction proceeds under mild conditions via the head-to-head oxidative coupling of two alkynes and a concomitant hydrohalogenation

Regio- and stereoselective syntheses of piperidine derivatives via ruthenium-catalyzed coupling of propargylic amides and allylic alcohols.

International audienceIntermolecular selective coupling of linear allylic alcohols and propargylic amides occurs in the presence of a catalytic amount of the cationic ruthenium complex [Cp*Ru(NCCH(3))(3)]PF(6) followed by condensation to generate six-membered cyclic enamides or hemiaminal ethers with water as the only side product

Access to 3-Oxindoles from Allylic Alcohols and Indoles

International audienceThe site-selective and regioselective allylation of 2-substituted indoles was performed by using a ruthenium(IV) precatalyst containing a phosphine-sulfonate chelate. Mono-, di-, and triallylated indoles were selectively obtained depending on the reaction conditions with the formation of water as the only byproduct. The preparation of 3-oxindole derivatives was then successfully performed owing to air oxidation of the corresponding allylated indoles. Diallylated pseudoindoxyls were proven to be good synthons to perform cyclization through a ring-closing metathesis reaction to afford the corresponding tricyclic adducts. The photophysical properties of the 3-oxindoles were measured, and some of the compounds showed strong fluorescence in water

Ruthenium-Catalyzed Synthesis of Functional Conjugated Dienes via Addition of two Carbene Units to Alkynes

International audienceThe reaction of a variety of alkynes with N2CHSiMe3, in the presence of Cp*RuCl(cod) as the catalyst precursor, leads to the general formation of functional conjugated dienes. This selective formation results from the ruthenium-catalyzed creation of two carbon−carbon double bonds in a single step under mild conditions. Terminal alkynes produce 1,4-bistrimethylsilylbuta-1,3-dienes with Z stereoselectivity for the less hindered double bond whereas disubstituted alkynes favor E-configuration for the same double bond. Diynes react also as monoalkynes, and only one triple bond is transformed to give disilylated dienynes. The reaction can be applied to the in situ desilylation in methanol and formation of monosilylated dienes. The catalytic formation of 1,4-bisfunctional buta-1,3-dienes can also take place with N2CHCO2Et and N2CHPh. The reaction can be understood by addition of two carbene units to triple bonds. An initial [2 + 2] addition of the Ru═CHSiMe3 bond with the alkyne triple bond leads to an alkenyl ruthenium-carbene species capable of coordinating a second carbene unit to produce conjugated dienes

One-Step Synthesis of Strained Bicyclic Carboxylic and Boronic Amino Esters via Ruthenium-Catalysed Tandem Carbene Addition/Cyclopropanation of Enynes

International audienceThe reaction of 1,6- and 1,7-enynes, derived from carboxylic and boronic amino acids, with diazo compounds in the presence of the (cyclooctadiene)(pentamethylcyclopentadiene)ruthenium chloride complex [RuCl(cod)(C5Me5)] catalyst leads to the formation of strained bicyclic proline or homoproline derivatives in good yields. This catalytic transformation proceeds under mild conditions, in one step from easily accessible enynes and was applied to various protecting groups. High stereoselectivities for the created alkenyl chain and excellent diastereoselectivities for proline derivatives were obtained