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An efficient approach for the fast modification of arylphosphine oxides involving ruthenium(II)-catalyzed C−H bond alkylation with functional alkenes versus alkenylation has been developed depending on the acidic reaction conditions. Using this methodology, a few examples of desymmetrization of diarylphosphine oxides has allowed the formation of phosphorus derivatives containing three different substituents. After reduction of the phosphine oxide, this method allows the formation of aryl phosphines bearing a flexible pendent carboxylate. [ABSTRACT FROM AUTHOR]

The metal-catalysed successive activation and functionalisation of sp2 C–H bonds is the at heart of synthetic innovations for the development of C–C bond cross-coupling processes. Against expectation catalytic C–H bond transformations can be performed in water as an available, renewable, safe solvent but most importantly as a partner improving the catalyst activity. The objective of the review is to present the catalytic successes for C–H bond transformations in water, discovered mainly during the last six years and involving mostly palladium and ruthenium catalysts, often with the help of a carboxylate partner for the initial key C–H bond deprotonation. Water is beneficial for the direct catalytic arylation with (hetero)aryl halides of functional arene ortho C–H bonds with pyridine, pyrazole, oxazoline, imine, urea, amide… directing groups leading to functional biaryl derivatives, polyheterocycles and polydentate ligands. Metal-catalysed activation of the sp2 C–H bond in water also allows the cross-coupling reaction of two different C–H bonds in the presence of an oxidant and regioselective alkenylations of arenes, heterocycles and functional alkenes are now controlled. Annulation reactions via insertion of alkynes into both activated C–H and heteroatom–hydrogen bonds in water constitute new routes to heterocycles. [ABSTRACT FROM AUTHOR]

Acrylonitrile has become a renewable material arising from glycerol. It can now be used as an available key product to introduce a nitrogen-containing functionality into a molecule by cross-metathesis. This review successively presents the developments of catalytic cross-metathesis of acrylonitrile with functional alkenes: (i) the first steps of cross-metathesis of acrylonitrile with simple terminal alkenes, of which the successes were linked to the progressive discoveries of efficient alkene metathesis catalysts, (ii) some contributions of this catalytic reaction to synthesis of complex molecules and (iii) the access to renewable α,̉-bifunctional compounds by acrylonitrile cross-metathesis with fatty acid derivatives, arising from plant oils. The combination of the renewable acrylonitrile and fatty acid derivatives, by catalysis under mild conditions with only ethylene as a by-product, constitutes a clear contribution to green chemistry for the production of useful intermediates. [ABSTRACT FROM AUTHOR]

The sp³C-H bond functionalisation of 2-pyridyl ethanols upon reaction with alkenes, in the presence of a [RuCl2(arene)]2 catalyst and Cu(OAc)2-H2O, is performed under mild conditions without additional base. This reaction proceeds via a tandem alcohol dehydrogenation/alkylation with alkenes of the resulting ketone at its a sp³C-H bond. [ABSTRACT FROM AUTHOR]

The article discusses a study on the development on the ruthenium (RU) (II)-catalyzed transformation of carbon-hydrogen (C-H) bonds into C-C bonds until the end of 2011. It states that most of the reactions of the bonds have been examined under the carbon dioxide (CO) pressure. It also relates that the direct arylations with heteroarylhalides of arenes and alkenes were first discovered with the association of RU catalytic systems.

A variety of ruthenium–allenylidene complexes were produced in two steps from the simple RuCl2(dmso)4 precursor: the neutral RuCl2(&z.dbnd6;C&z.dbnd6;C&z.dbnd6;CR2)(PCy3)n(dmso)m and the cationic [RuCl(&z.dbnd6;C&z.dbnd6;C&z.dbnd6;CR2)(PCy3)n(dmso)m]TfO complexes. Some of them have been evaluated for polymerisation of norbornene and cyclooctene, and constitute the first example of active Ru&z.dbnd6;C&z.dbnd6;C&z.dbnd6;CR2 catalysts for ring opening metathesis polymerisation (ROMP). The most active system is the cationic [RuCl(&z.dbnd6;C&z.dbnd6;C&z.dbnd6;CPh2)(PCy3)(dmso)2]TfO complex 5 which leads in PhCl at 80 °C to 90% of polycyclooctene with a polydispersity of 1.89 and 69% of cis-configuration of CH&z.dbnd6;CH bonds. The presence of an electron-donating group on the aryl substituents (p-OMe) drastically favours both yield and low polydispersity of the polymer. [Copyright &y& Elsevier]

The allenylidene-ruthenium complexes [(η6-arene)RuCl(CCCR2)(PR'3))OTf (R2 = Ph; fluorene, Ph, Me; PR'3 = PCy3, PiPr3, PPh3) (OTf = CF3SO3) on protonation with HOTf at -40 °C are completely transformed into alkenylcarbyne complexes [(η6-p-cymene)RuCl(CCHCR2)(PR3)](OTf)2. At -20 °C the latter undergo intramolecular rearrangement of the allenylidene ligand, with release of HOTf, into the indenylidene group in derivatives ((η6-arene) RuCI(indenylidene)(PR3)]OTf. The in situ-prepared indenyliclene-ruthenium complexes are efficient catalyst precursors for ring-opening metathesis polymerization of cyclooctene and cyclopentene, reaching turnover frequencies of nearly 300 s at room temperature. Isolation of these derivatives improves catalytic activity for the ring-closing metathesis of a variety of dienes and enynes. A mechanism based on the initial release of arene ligand and the in situ generation of the active catalytic species RuCI(OTf)(CH2)(PR3) is proposed. [ABSTRACT FROM AUTHOR]

Bis-oxazolines 1a–c and 2-benzothiazol-2-ylmethyl-benzooxazole (1d) (N&z.sbnd;N) react with [RuCl2(p-cymene)]2 in polar solvent with NH4BF4 or NH4PF6 and lead to ionic arene-ruthenium complexes [RuCl(N&z.sbnd;N)(p-cymene)]+X− (3a–d) in quantitative yields. These complexes are easily deprotonated on the bridging methylene group and their electrochemical study shows the subtle influence of the substituents on the electron richness of the ruthenium atom. Complex 3b in the presence of both 1,3-bis(2,6-diisopropylphenyl)imidazolinium chloride 6 and Cs2CO3 (1/1/2) catalyses the selective transformation of bis-allyl ether into γ,δ-unsaturated aldehyde via successive alkene isomerisation and Claisen rearrangement. [Copyright &y& Elsevier]

The article reports on regioselective catalytic oxidative couplings of functional alkynes and alkenes at electron-rich ruthenium precatalysts and explores the allenylboronate reactivity. Among functional allenes, allenylboronates have never been involved in catalytic transformations despite their potential for formation of small cycle intermediates. Researchers report the first direct access to rigid 1,3-dimethyl-enecyclobutane derivatives via an original head-to-head cyclodimerization of allenyl boronate, catalyzed by a ruthenium catalyst.

A facile protocol is developed for the dehydrogenation of N-alkylbenzenesulfonamides to give the corresponding N-alkenyl derivatives. [ABSTRACT FROM AUTHOR]