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We reported herein rhodium(III)-catalyzed C-H activation and annulation reactions for the synthesis of bulky phosphine ligands by using 1-alkynylphosphine sulfides as key starting materials. In the presence of [Cp*RhCl2]2 (5 mol %) and CsOAc (2.0 equiv), various N-(pivaloyloxy)benzamides (3.0 equiv) could react smoothly with 1-alkynylphosphine sulfides at 40 °C in MeOH/CF3CH2OH cosolvent without external oxidant. Using [CpPhRhCl2]2 as catalyst, the reaction can be performed under less loading of benzamides (2.0 equiv) and milder reaction conditions (25 °C) with higher regioselectivity. In a sequential cyclization/desulfidation process, this new method provides a variety of bulky heteroarylphosphines with an isoquinolin-1(2H)-one motif. [ABSTRACT FROM AUTHOR]

Reactions of a series of unsymmetrically substituted N-heterocyclic carbene ligands with Ru3(CO)12afforded a variety of mononuclear (1, 2), trinuclear (3, 4, 5, and 5′), and tetranuclear (6, 7) ruthenium complexes via intramolecular ruthenium-mediated sp2and sp3C–H bond activations. Complexes 6and 7include an octahedral cluster skeleton consisting of four ruthenium atoms and two metalated carbon atoms. The formation of this type of ruthenium clusters is proposed to involve the initial C–C double-bond migration and subsequent sp2C–H bond activations. All new complexes were fully characterized, and the molecular structures of 1, 2, 5, 6, and 7were determined by X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

Thermal treatment of dihydrooctamethyl-s-indacene with Ru3(CO)12afforded the trinuclear and tetranuclear complexes Ru3(η5:η5:η2-C20H24)(CO)7(1) and Ru4(η5:η4:η1-C20H24)(μ-CO)2(CO)7(2), via intramolecular sp3C−H bond activation, and the mononuclear complex Ru(η5-C20H25)(CO)2Cl (3), which might be formed via chlorination of a terminal hydride complex during column chromatography. Reaction of 1,2,3,4,7-pentamethylindene with Ru3(CO)12also yielded the tetranuclear complex Ru4(η5:η3:η2-C14H16)(CO)9(4) via the same sp3C−H bond activation, together with the dinuclear complex [(η5-C9H2Me5)Ru(CO)]2(μ-CO)2(5). In contrast, reaction of 4,7-dimethylindene with Ru3(CO)12gave only the dinuclear complex [(η5-C9H5Me2)Ru(CO)]2(μ-CO)2(6). The molecular structures of all six complexes have been determined by single-crystal X-ray diffraction analysis. [ABSTRACT FROM AUTHOR]

The intramolecular sp2and sp3C–H activated products, as well as the monometalated products, based on the “(p-cymene)Ru(NHC)” framework were synthesised by treatment of a series of NHCs (1-R-3-methylimidazol-2-ylidene [R = Ph (1), Bn (2), t-Bu (3), i-Pr (4), Mes (5), Cy (6)] and 1,3-bis(isopropyl)imidazol-2-ylidene (7)) with [(p-cymene)RuCl2]2under mild conditions. A new NHC precursor (1-tert-butyl-3-phenyl-4,5-dihydro-imidazol-2-ylidene) was also designed to compare the reactivity of sp2C–H and sp3C–H bonds upon cyclometalation, and only the sp3C–H activated product (8) was observed. The factors that possibly determine the selectivity of intramolecular sp2or sp3C–H activation are elucidated by a series of experiments. In the cases where activation of both sp2C–H and sp3C–H is possible, steric factors overrode the others to dominate the regioselectivity of activation. All complexes were characterised by 1H NMR, 13C NMR and HRMS spectra. The molecular structures of 1, 3, 5, 6, 7, and 8were confirmed by X-ray diffraction. [ABSTRACT FROM AUTHOR]

Rh(III)-catalyzed carbocyclization reactions of 3-(indolin-1-yl)-3-oxopropanenitriles with alkynes and alkenes have been developed to form 1,7-fused indolines through C-H activation. These reactions have a broad range of substrates and high yields. Unsymmetrical aryl-alkyl substituted alkynes proceeded smoothly with high regioselectivity. Electron-rich alkynes could undergo further oxidative coupling reaction to form polycyclic compounds. For alkenes, 1,2-dihydro-4H-pyrrolo[3,2,1-ij]quinolin-4-ones were formed via C(sp²)-H bond alkenylation and C(sp²)-H, C(sp³)-H oxidative coupling reactions. [ABSTRACT FROM AUTHOR]