Allylic Carbon–Carbon Double Bond Directed Pd-Catalyzed Oxidative <i>ortho</i>-Olefination of Arenes

Pd-catalyzed selective <i>ortho</i>-olefination of arenes assisted by an allylic C–C double bond at room temperature using O₂ as a terminal oxidant is described. A possible mechanism involving the initial coordination of allylic CC bond to Pd followed by selective <i>o</i>-C–H bond metalation is proposed

Pd-Catalyzed π‑Chelation Assisted <i>ortho</i>-C–H Activation and Annulation of Allylarenes with Internal Alkynes

The synthesis of highly substituted naphthalenes from allylarenes and alkynes is described. This reaction proceeds via π-coordination of an allylic carbon–carbon double bond to the Pd(II) center and is followed by <i>ortho</i> selective C–H bond activation

Allylic Carbon–Carbon Double Bond Directed Pd-Catalyzed Oxidative <i>ortho</i>-Olefination of Arenes

Pd-catalyzed selective <i>ortho</i>-olefination of arenes assisted by an allylic C–C double bond at room temperature using O₂ as a terminal oxidant is described. A possible mechanism involving the initial coordination of allylic CC bond to Pd followed by selective <i>o</i>-C–H bond metalation is proposed

Rh^III-Catalyzed [4 + 1] Annulations of 2‑Hydroxy- and 2‑Aminobenzaldehydes with Allenes: A Simple Method toward 3‑Coumaranones and 3-Indolinones

A novel method for the regio- and stereoselective synthesis of substituted 3-coumaranones from salicylaldehydes and allenes using a rhodium­(III) catalyst has been developed. This procedure gives access to new 2-vinyl-substituted 3-coumaranone compounds. The method involves a Rh^III-catalyzed aldehyde C–H activation and annulation reactions. Moreover, this Rh^III-catalyzed [4 + 1] annulation reaction has been applied to 2-aminobenzaldehydes to afford 2,2-disubstituted 3-indolinones

Ruthenium-Catalyzed C–H Alkynylation of Aromatic Amides with Hypervalent Iodine–Alkyne Reagents

An efficient C–H activation method for the <i>ortho</i> alkynylation of aromatic <i>N-</i>methoxyamides with hypervalent iodine–alkyne reagent using a ruthenium catalyst is described. The reaction proceeds under mild reaction conditions with broad substrate scope. A possible catalytic cycle involving a ruthenium carboxylate assisted C–H bond cleavage is proposed from the preliminary mechanistic evidence

Cobalt-Catalyzed Hydroarylative Cyclization of 1,6-Enynes with Aromatic Ketones and Esters via C–H Activation

A highly chemo- and stereoselective cobalt-catalyzed hydroarylative cyclization of 1,6-enynes with aromatic ketones and esters to synthesize functionalized pyrrolidines and dihydrofurans is described. A mechanism involving cobaltacycle triggered C–H activation of aromatic ketones and esters was proposed

Cobalt(III)-Catalyzed [5 + 1] Annulation for 2<i>H</i>‑Chromenes Synthesis via Vinylic C–H Activation and Intramolecular Nucleophilic Addition

A new cobalt-catalyzed phenolic OH-assisted C–H functionalization of 2-vinylphenols with allenes to give various 2<i>H</i>-chromenes is described. It is the first time that allenes are used as the coupling partners in the cobalt-catalyzed C–H activation reactions. In most cases, cobalt-catalyzed oxidative annulation of arenes with alkenes or alkynes via C–H activation gave [4 + 2] or [3 + 2] cyclization products, but the present catalytic reaction afforded an oxidative [5 + 1] cyclization products with the allenes acting as a one-carbon coupling partner. The catalytic reaction is proposed to proceed via the C–H activation of the vinyl group, allene insertion, and an unusual intramolecular regioselective phenoxide addition

Palladium-Catalyzed Dehydrogenative β‑Arylation of Simple Saturated Carbonyls by Aryl Halides

A versatile palladium-catalyzed synthesis of highly substituted α,β-unsaturated carbonyl compounds has been developed. In contrast to the known Heck-type coupling reaction of unsaturated carbonyl compounds with aryl halides, the present methodology allows the use of stable and readily available saturated carbonyl compounds as the alkene source. In addition, the reaction proceeds well with low catalyst loadings and does not require any expensive metal oxidants or ligands. A variety of saturated aldehydes, ketones, and esters are compatible for the reaction with aryl halides under the developed reaction conditions to afford α,β-unsaturated carbonyl compounds in good to excellent yields. A possible reaction mechanism involves a palladium-catalyzed dehydrogenation followed by Heck-type cross couplings

Ruthenium-Catalyzed C–H Alkynylation of Aromatic Amides with Hypervalent Iodine–Alkyne Reagents

An efficient C–H activation method for the <i>ortho</i> alkynylation of aromatic <i>N-</i>methoxyamides with hypervalent iodine–alkyne reagent using a ruthenium catalyst is described. The reaction proceeds under mild reaction conditions with broad substrate scope. A possible catalytic cycle involving a ruthenium carboxylate assisted C–H bond cleavage is proposed from the preliminary mechanistic evidence

Ruthenium-Catalyzed C–H Alkynylation of Aromatic Amides with Hypervalent Iodine–Alkyne Reagents

An efficient C–H activation method for the <i>ortho</i> alkynylation of aromatic <i>N-</i>methoxyamides with hypervalent iodine–alkyne reagent using a ruthenium catalyst is described. The reaction proceeds under mild reaction conditions with broad substrate scope. A possible catalytic cycle involving a ruthenium carboxylate assisted C–H bond cleavage is proposed from the preliminary mechanistic evidence