Unusual Kinetics Induced by Ligands in Rhodium(III)-Catalyzed Dehydrogenative Olefination Reactions.

In this study, we investigate the effects of ligands on C-H activation during rhodium(III)-catalyzed C-H bond olefination reactions using well-defined [CpRh] catalytic systems with three representative Cp (Cp (η-CH), Cp (η-CMeCF), and Cp* (η-CMe)) ligands. Our results demonstrate that C-H activation as the rate-limiting step is significantly influenced by the steric properties of the Cp ligands. Moreover, we observe a dramatic acceleration of the simple [CpRh]-catalyzed C-H olefination reaction with acid coproducts such as HOAc, implying an autocatalytic C-H activation process.

Cyclometalated Platinum(II) Metallomesogens Based on Half-Disc-Shaped β-Diketonate Ligands with Hexacatenar: Crystal Structures, Mesophase Properties, and Semiconductor Devices.

A series of new half-disc-shaped platinum(II) complexes [Pt(ppy)(AL-6OCH)] (, [Pt(ppyF)(AL-6OCH)] (, and [Pt(ppyCF)(AL-6OCH)] ( (AL-6OCH = 1,3-bis(3,4,5-trialkoxyphenyl)propane-1,3-dionato; = 1, 6, 12) with concise structures have been designed and synthesized, in which 2-phenylpyridine (ppy) derivatives were used as cyclometalated ligands and hexacatenar β-diketonate derivatives AL-6OCH as auxiliary ligands. The single-crystal data of the methoxy diketonate analogues , , and indicate that they all display excellent square planarity. These platinum(II) complexes show a certain emission tunability (ranging from λ = 506-535 nm) by the introduction of fluorine or trifluoromethyl into ppy.

Trisulfur radical anion-triggered stitching thienannulation: rapid access to largely π-extended thienoacenes.

Largely π-extended rylene diimide-fused thienoacenes, a new family of fully fused electron donor-acceptor (D-A) molecules, have been readily synthesized by a novel trisulfur radical anion (S˙)-triggered stitching thienannulation strategy. The ladder-type fused thiophene cores are constructed in a stitching manner through multiple carbon-sulfur bond formation between acetylenic rylene dyes and S˙. A detailed mechanistic study of these stitching thienannulations unveiled the multiple reactivities of S˙.

Scalable Rhodium(III)-Catalyzed Aryl C-H Phosphorylation Enabled by Anodic Oxidation Induced Reductive Elimination.

Transition metal catalyzed C-H phosphorylation remains an unsolved challenge. Reported methods are generally limited in scope and require stoichiometric silver salts as oxidants. Reported here is an electrochemically driven Rh -catalyzed aryl C-H phosphorylation reaction that proceeds through H evolution, obviating the need for stoichiometric metal oxidants.

Efficient endo Cycloisomerization of Terminal Alkynols Catalyzed by a New Ruthenium Complex with 8-(Diphenylphosphino)quinoline Ligand and Mechanistic Investigation.

Several new ruthenium complexes supported by the P,N-donor ligand 8-(diphenylphosphino)quinoline (DPPQ) were synthesized, including [RuCl (DPPQ) ] (1), [Ru(μ-Cl)(DPPQ) ] (BPh ) (2), and [RuCl(DPPQ) Py](BF ) (3). Complex 2, with only 1 mol % loading, was found to be catalytically active for the endo cycloisomerization of various terminal alkynols to endo-cyclic enol ethers in moderate to excellent yields. In particular, the 7- and 8-endo heterocyclization can be achieved efficiently to give the seven-membered 3-benzoxepine and eight-membered 3-benzo[d]oxocine derivatives.

Rhodium-Catalyzed β-Selective Oxidative Heck-Type Coupling of Vinyl Acetate via C-H Activation.

An efficient Rh(III)-catalyzed direct ortho-C-H olefination of acetanilides with vinyl acetate was developed. This protocol provides a straightforward pathway to a series of (E)-2-acetamidostyryl acetates, giving access to indole derivatives following a simple hydrolysis/cyclization process.

Synthesis of α-Aminonaphthalenes via Copper-Catalyzed Aminobenzannulation of (o-Alkynyl)arylketones with Amines.

A copper-catalyzed aminobenzannulation of (o-alkynyl)arylketones with amines has been developed. This method features the use of a cheap copper catalyst, the facile annulation involving various amines, and the good functional group tolerance.

Copper-Catalyzed Direct C2-Benzylation of Indoles with Alkylarenes.

The copper-catalyzed regioselective cross-dehydrogenative coupling of N-pyrimidylindoles with benzylic C(sp(3))-H bonds has been developed. Di-tert-butyl peroxide was employed as a mild oxidant, and benzaldehyde proved to be an effective additive. This reaction provides a direct and pratical route to a variety of 2-benzylindoles.

Correction: Silver-mediated direct phosphorylation of benzothiazoles and thiazoles with diarylphosphine oxides.

Correction for 'Silver-mediated direct phosphorylation of benzothiazoles and thiazoles with diarylphosphine oxides' by Hui-Jun Zhang et al., Chem. Commun.

Highly Active Gold(I)-Silver(I) Oxo Cluster Activating sp³ C-H Bonds of Methyl Ketones under Mild Conditions.

The activation of C(sp(3))-H bonds is challenging, due to their high bond dissociation energy, low proton acidity, and highly nonpolar character. Herein we report a unique gold(I)-silver(I) oxo cluster protected by hemilabile phosphine ligands [OAu3Ag3(PPhpy2)3](BF4)4 (1), which can activate C(sp(3))-H bonds under mild conditions for a broad scope of methyl ketones (RCOCH3, R = methyl, phenyl, 2-methylphenyl, 2-aminophenyl, 2-hydroxylphenyl, 2-pyridyl, 2-thiazolyl, tert-butyl, ethyl, isopropyl). Activation happens via triple deprotonation of the methyl group, leading to formation of heterometallic Au(I)-Ag(I) clusters with formula RCOCAu4Ag4(PPhpy2)4(BF4)5 (PPhpy2 = bis(2-pyridyl)phenylphosphine).

Stabilizing Two Classical Antiaromatic Frameworks: Demonstration of Photoacoustic Imaging and the Photothermal Effect in Metalla-aromatics.

Antiaromatic species are substantially less thermodynamically stable than aromatic moieties. Herein, we report the stabilization of two classical antiaromatic frameworks, cyclobutadiene and pentalene, by introducing one metal fragment through the first [2+2] cycloaddition reaction of a late-transition-metal carbyne with alkynes. Experimental observations and theoretical calculations reveal that the metal fragment decreases the antiaromaticity in cyclobutadiene and pentalene simultaneously, leading to air- and moisture-stable products.

Rh/Cu-catalyzed multiple C-H, C-C, and C-N bond cleavage: facile synthesis of pyrido[2,1-a]indoles from 1-(pyridin-2-yl)-1H-indoles and γ-substituted propargyl alcohols.

An unusual Rh/Cu-catalyzed synthesis of pyrido[2,1-a]indoles starting from 1-(pyridin-2-yl)-1H-indoles and γ-substituted propargyl alcohols was presented. The multi-step cascade transformations formally involve the cleavage of two C-H, three C-C, and one C-N bonds with concomitant construction of two C-H, four C-C, and one C-N bonds with excellent chemoselectivity in one-pot reaction.

Silver-mediated direct phosphorylation of benzothiazoles and thiazoles with diarylphosphine oxides.

A silver nitrate-mediated, efficient phosphorylation of benzothiazoles and thiazoles with diarylphosphine oxides was developed. This process provides a convenient route for the synthesis of a variety of 2-diarylphosphoryl benzothiazoles and thiazoles which are promising precursors of a series of hemilabile P,N-ligands with small bite angles.

Rh(III)-Catalyzed Oxidative Coupling of Benzoic Acids with Geminal-Substituted Vinyl Acetates: Synthesis of 3-Substituted Isocoumarins.

The Rh(III)-catalyzed C-H activation initiated cyclization of benzoic acids with electron-rich geminal-substituted vinyl acetates was described. The reaction was employed to prepare a range of 3-aryl and 3-alkyl substituted isocoumarins selectively.

Stabilization of anti-aromatic and strained five-membered rings with a transition metal.

Anti-aromatic compounds, as well as small cyclic alkynes or carbynes, are particularly challenging synthetic goals. The combination of their destabilizing features hinders attempts to prepare molecules such as pentalyne, an 8π-electron anti-aromatic bicycle with extremely high ring strain. Here we describe the facile synthesis of osmapentalyne derivatives that are thermally viable, despite containing the smallest angles observed so far at a carbyne carbon.

A half-sandwich 1,2-azaborolyl ruthenium complex: synthesis, characterization, and evaluation of its catalytic activities.

A half-sandwich 1,2-azaborolyl (Ab) ruthenium complex, (Ab-C≡CPh)RuCl(PPh3)2 (1), has been synthesized by treating RuCl2(PPh3)3 with lithium 1,2-azaborolide L-1, or by treating either RuCl2(PPh3)3 or RuHCl(PPh3)3 directly with 1,2-azaborole LH-1. It is evaluated as a suitable precatalyst in [2 + 2] cycloadditions of norbornene derivatives with DMAD and in atom transfer radical additions of halogenated compounds with olefins.

A rhodamine-deoxylactam based sensor for chromo-fluorogenic detection of nerve agent simulant.

N-(rhodamine B)-deoxylactam-5-amino-1-pentanol (dRB-APOH) was designed and prepared as the chromo-fluorogenic sensor for detection of a nerve agent simulant via analyte triggered tandem phosphorylation and opening of the intramolecular deoxylactam. The successful detection of diethyl chlorophosphate suggests the utility of rhodamine-deoxylactams as the chromo-fluorogenic signal reporting platform for design of sensors targeting reactive chemical species via various chemistries.

Studies on the Synthetic System of V/Ag/S Cluster Compounds and Structural Characterizations of V(2)AgS(4), V(2)Ag(2)S(4), and V(2)O(2)(&mgr;-S)(2) Complexes.

The reaction system (NH(4))(3)VS(4)/Ag(PPh(3))(2)Cl/R(2)dtcNa in CH(3)CN was studied to afford two V(2)Ag(1)(-)(2)S(4) cubanelike cluster compounds and a trinuclear V(3)O(3)S(2) complex. (Et(4)N)[V(2)AgS(4)(Me(2)dtc)(2)(PPh(3))].(1)/(2)CH(3)CN ([Et(4)N]1.