Synthesis, Structures, and Norbornene ROMP Behavior of <i>o</i>-Aryloxide-N-Heterocyclic Carbene <i>p</i>-Cymene Ruthenium Complexes

Treatment of the <i>o</i>-hydroxyaryl imidazolium proligands (2-OH-3,5-^<i>t</i>Bu₂C₆H₂)­(R)­(C₃H₃N₂)⁺Br^– (R = ^<i>i</i>Pr (<b>1a</b>), ^<i>t</i>Bu (<b>1b</b>), Ph (<b>1c</b>), Mes (<b>1d</b>)) with 3 equiv of Ag₂O afforded the corresponding silver complexes <b>2a</b>–<b>d</b>. The subsequent metal-exchange reactions with [(<i>p</i>-cymene)­RuCl₂]₂ at room temperature yielded the desired <i>o</i>-aryloxide-N-heterocyclic carbene <i>p</i>-cymene ruthenium complexes <b>3a</b>–<b>d</b> in nearly quantitative yields. All the complexes were characterized by ¹H and ¹³C NMR, high-resolution mass spectrometry (HRMS), and elemental analysis. The molecular structure of complex <b>3b</b> was determined by single-crystal X-ray diffraction analysis. The ring-opening metathesis polymerization (ROMP) of norbornene (NBE) with <b>3a</b>–<b>d</b> was studied. Among them, complex <b>3d</b> showed high activity and efficiency toward ROMP of NBE at 85 °C without the need for any cocatalyst, and polymers with very high molecular weight (>10⁶) and narrow molecular weight distributions were obtained. This complex can also catalyze the alternating copolymerization of NBE and cyclooctene (COE)

Synthesis, Structures, and Norbornene ROMP Behavior of <i>o</i>-Aryloxide-N-Heterocyclic Carbene <i>p</i>-Cymene Ruthenium Complexes

Treatment of the <i>o</i>-hydroxyaryl imidazolium proligands (2-OH-3,5-^<i>t</i>Bu₂C₆H₂)­(R)­(C₃H₃N₂)⁺Br^– (R = ^<i>i</i>Pr (<b>1a</b>), ^<i>t</i>Bu (<b>1b</b>), Ph (<b>1c</b>), Mes (<b>1d</b>)) with 3 equiv of Ag₂O afforded the corresponding silver complexes <b>2a</b>–<b>d</b>. The subsequent metal-exchange reactions with [(<i>p</i>-cymene)­RuCl₂]₂ at room temperature yielded the desired <i>o</i>-aryloxide-N-heterocyclic carbene <i>p</i>-cymene ruthenium complexes <b>3a</b>–<b>d</b> in nearly quantitative yields. All the complexes were characterized by ¹H and ¹³C NMR, high-resolution mass spectrometry (HRMS), and elemental analysis. The molecular structure of complex <b>3b</b> was determined by single-crystal X-ray diffraction analysis. The ring-opening metathesis polymerization (ROMP) of norbornene (NBE) with <b>3a</b>–<b>d</b> was studied. Among them, complex <b>3d</b> showed high activity and efficiency toward ROMP of NBE at 85 °C without the need for any cocatalyst, and polymers with very high molecular weight (>10⁶) and narrow molecular weight distributions were obtained. This complex can also catalyze the alternating copolymerization of NBE and cyclooctene (COE)

Synthesis, Reactivities, and Catalytic Properties of Iodo-Bridged Polymeric Iridium Complexes with Flexible Carbon Chain-Bridged Bis(tetramethylcyclopentadienyl) Ligands

Dinuclear iridium complexes [(C₅Me₄)­(CH₂)_<i>n</i>­(C₅Me₄)]­[Ir­(COD)]₂ (<b>2a</b>: <i>n</i> = 2; <b>2b</b>: <i>n</i> = 3; <b>2c</b>: <i>n</i> = 4) are obtained from the reactions of the corresponding dilithium salts Li₂[(C₅Me₄)­(CH₂)_<i>n</i>­(C₅Me₄)] (<i>n</i> = 2–4) with [Ir­(μ-Cl)­(COD)]₂. Further oxidation of <b>2</b> affords iodo-bridged polymeric iridium complexes [(C₅Me₄)­(CH₂)_<i>n</i>­(C₅Me₄)­(IrI₂)₂]_<i>m</i> (<b>3a</b>: <i>n</i> = 2; <b>3b</b>: <i>n</i> = 3; <b>3c</b>: <i>n</i> = 4). Dinuclear iridium complexes [(C₅Me₄)­(CH₂)_<i>n</i>­(C₅Me₄)]­[IrI₂(PPh₃)]₂ (<b>4a</b>: <i>n</i> = 2; <b>4b</b>: <i>n</i> = 3; <b>4c</b>: <i>n</i> = 4) and [(C₅Me₄)­(CH₂)_<i>n</i>­(C₅Me₄)]­[IrI₂(CO)]₂ (<b>5b</b>: <i>n</i> = 3; <b>5c</b>: <i>n</i> = 4) are obtained from the reactions of <b>3</b> with PPh₃ and CO, respectively. Dinuclear dicarbonyl iridium complexes [(C₅Me₄)­(CH₂)_<i>n</i>­(C₅Me₄)]­[Ir­(CO)₂]₂ (<b>6b</b>: <i>n</i> = 3; <b>6c</b>: <i>n</i> = 4) are obtained from the reactions of <b>3</b> with Zn and CO. Additionally, the cyclometalated dinuclear iridium complexes <b>7b</b>,<b>c</b>, <b>8b</b>,<b>c</b>, <b>9b</b>,<b>c</b>, and <b>10b</b>,<b>c</b> are obtained from the reactions of <b>3</b> with the corresponding nitrogen ligands in the presence of KOH. The molecular structures of complexes <b>2a</b>, <b>4a</b>, <b>5b</b>, <b>6c</b>, and <b>7b</b> have been determined by single-crystal X-ray diffraction analysis. Moreover, we found that complexes <b>3</b> and <b>4</b> are efficient catalysts for the selective amine cross-coupling reaction

Palladium-Catalyzed Direct Dehydrogenative Annulation of Ferrocenecarboxamides with Alkynes in Air

A novel method to synthesize racemic ferrocene­[1,2-<i>c</i>]­pyridine-3­(4<i>H</i>)-ones via Pd-catalyzed direct dehydrogenative annulations of ferrocenecarboxamides with internal alkynes in air has been developed. Both alkyl and aryl ferrocenecarboxamides can be applied as effective substrates

Ruthenium-Catalyzed Regioselective C2 Alkenylation of Indoles and Pyrroles via C–H Bond Functionalization

An efficient ruthenium-catalyzed oxidative coupling of indoles and pyrroles with various alkenes at the C2-position assisted by employing the <i>N</i>,<i>N</i>-dimethylcarbamoyl moiety as a directing group is reported. The catalytic reaction proceeds in an excellent regio- and stereoselective manner

Ruthenium-Catalyzed Oxidative C–H Bond Olefination of <i>N</i>-Methoxybenzamides Using an Oxidizing Directing Group

Ruthenium-catalyzed oxidative C–H bond olefination of <i>N</i>-methoxybenzamides using an oxidizing directing group with a broad substrate scope is reported. The reactions of <i>N</i>-methoxybenzamides with acrylates in MeOH and styrene (or norbornadiene) in CF₃CH₂OH afforded two types of products

Ruthenium-Catalyzed Regioselective C2 Alkenylation of Indoles and Pyrroles via C–H Bond Functionalization

An efficient ruthenium-catalyzed oxidative coupling of indoles and pyrroles with various alkenes at the C2-position assisted by employing the <i>N</i>,<i>N</i>-dimethylcarbamoyl moiety as a directing group is reported. The catalytic reaction proceeds in an excellent regio- and stereoselective manner

Rhodium(III)-Catalyzed Intermolecular Amidation with Azides via C(sp³)–H Functionalization

The amidation reactions of 8-methylquinolines with azides catalyzed by a cationic rhodium­(III) complex proceed efficiently to give quinolin-8-ylmethanamine derivatives in good yields via C­(sp³)–H bond activation under external oxidant-free conditions. A catalytically competent five-membered rhodacycle has been isolated and characterized, revealing a key intermediate in the catalytic cycle

Rhodium-Catalyzed Cascade Oxidative Annulation Leading to Substituted Naphtho[1,8-<i>bc</i>]pyrans by Sequential Cleavage of C(sp²)–H/C(sp³)–H and C(sp²)–H/O–H Bonds

The cascade oxidative annulation reactions of benzoylacetonitrile with internal alkynes proceed efficiently in the presence of a rhodium catalyst and a copper oxidant to give substituted naphtho­[1,8-<i>bc</i>]­pyrans by sequential cleavage of C­(sp²)–H/C­(sp³)–H and C­(sp²)–H/O–H bonds. These cascade reactions are highly regioselective with unsymmetrical alkynes. Experiments reveal that the first-step reaction proceeds by sequential cleavage of C­(sp²)–H/C­(sp³)–H bonds and annulation with alkynes, leading to 1-naphthols as the intermediate products. Subsequently, 1-naphthols react with alkynes by cleavage of C­(sp²)–H/O–H bonds, affording the 1:2 coupling products. Moreover, some of the naphtho­[1,8-<i>bc</i>]­pyran products exhibit intense fluorescence in the solid state

Synthesis and Alkyne Insertion Reactions of NHC-Based Cyclometalated Ruthenium(II) Complexes

The series of NHC-based cyclometalated ruthenium­(II) complexes <b>2a</b>–<b>k</b> were synthesized by the reactions of aryl-substituted imidazolium salts with [(<i>p</i>-cymene)­RuCl₂]₂ under mild conditions. These complexes could react with alkynes in MeOH at 80 °C, through alkyne insertion and subsequent reductive elimination, to give the new kinds of imidazolium salts <b>3a</b>–<b>q</b> in high yields. All new compounds were fully characterized, and the molecular structures of <b>2a</b>–<b>d</b>,<b>f</b>,<b>g</b>,<b>i</b>–<b>k</b> were determined by single-crystal X-ray diffraction analysis