Direct amidation of azoles with formamides via metal-free C–H activation in the presence of tert-butyl perbenzoate

A novel and simple method for the direct amidation of azoles with formamides has been developed. The reaction could occur smoothly in the presence of tert-butyl perbenzoate (TBPB) as an oxidant under metal- and base-free conditions. Direct dehydrogenative cross-coupling of formamides and azoles generated the corresponding products in good yields.

Copper-Catalyzed Dehydrogenative Cross-Coupling Reactions of N-para-Tolylamides through Successive C[BOND]H ActivationSynthesis of 4H-3,1-Benzoxazines

A novel annulation reaction of readily available tolylamides was catalyzed by Cu(OTf)₂ in the presence of Selectfluor and water through successive intermolecular CH activated dehydrogenative cross-coupling reactions of benzylic methyl C(sp³)H and aromatic C(sp²)H bonds, and subsequent intramolecular CO bond formation.

Angew. Chem. Int. Ed. 2011, DOI: 10.1002/anie.201101391

Ruthenium-Catalyzed Oxidative C–H Bond Alkenylations in Water: Expedient Synthesis of Annulated Lactones

Ruthenium-catalyzed cross-dehydrogenative C–H bond alkenylations occurred efficiently in environmentally benign water, which was exploited for an oxidative phthalide synthesis with ample scope. Mechanistic studies provided strong evidence for the oxidative alkenylation to proceed by an irreversible C–H bond metalation via acetate assistance.

Palladium-/Copper-Catalyzed Regioselective Amination and Chloroamination of Indoles

A palladium-/copper-catalyzed intermolecular C–H amination reaction of indoles has been developed. This reaction proceeds in good to excellent yields to produce a variety of 2-amino-substituted indoles and exhibits excellent regioselectivity at room temperature. Furthermore, chloroamination of indoles provides a simple method for the construction of C–N and C–Cl bonds in one step.

Org Lett 2011.

Copper-catalyzed direct thiolation of azoles with aliphatic thiols

Cu(II)-catalyzed direct thiolation of azoles with thiols is described via intermolecular C–S bond formation/C–H functionalization under oxidative conditions. Both aryl thiols and aliphatic thiols are used as coupling partners, and furnished the thiolation products in moderate to good yields. The reaction is compatible with a wide range of heterocycles including oxazole, thiazole, imidazole and oxadiazole.

Magical Power of Transition Metals: Past, Present, and Future (Nobel Lecture)

Tools for chemists: The Nobel Prize in Chemistry 2010 was awarded for research on palladium-catalyzed cross-coupling in organic synthesis. Two of the Laureates, A. Suzuki and E. Negishi, report here first hand on the historical development and the current status of this research.

1. Prof.  Ei-ichi Negishi, Angew. Chem. Int. Ed. 2011, 

DOI: 10.1002/anie.201101380

Cross-Coupling Reactions Of Organoboranes: An Easy Way To Construct C[BOND]C Bonds (Nobel Lecture)

Tools for chemists: The Nobel Prize in Chemie 2010 was awarded for research on palladium-catalyzed cross-coupling in organic synthesis. Two of the Laureates, A. Suzuki and E. Negishi, report here first hand on the historical development and the current status of this research.

Prof. Akira Suzuki, Angew. Chem. Int. Ed. 2011, 

DOI: 10.1002/anie.201101379

Nickel-Catalyzed CH Arylation of Azoles with Haloarenes: Scope, Mechanism, and Applications to the Synthesis of Bioactive Molecules

New couples: Novel Ni-based catalytic systems for the CH arylation of azoles with haloarenes have been developed (see scheme). Mechanistic studies as well as applications to the synthesis of biologically active compounds (febuxostat, tafamidis, and texaline) are also described.

Itami, Chem. Eur. J. 2011, DOI: 10.1002/chem.201101091

Palladium-Catalyzed Selective Dehydrogenative Cross-Couplings of Heteroarenes

A nice couple: Two heteroaryls bearing no prefunctionalization can be cross-coupled efficiently through Pd^II catalysis to afford the biheteroaryl. The selectivity of this transformation probably finds its origin in the two mechanistically different metalation steps of CH bonds.

1. Prof. Dr. Frank Glorius, Angew. Chem. int. Ed, 2011, 
DOI: 10.1002/anie.201103106

Selective ortho-Bromination of Substituted Benzaldoximes Using Pd-Catalyzed C–H Activation: Application to the Synthesis of Substituted 2-Bromobenzaldehydes

Substituted 2-bromobenzaldehydes were synthesized from benzaldehydes using a three-step sequence involving a selective palladium-catalyzed ortho-bromination as the key step. O-Methyloxime serves as a directing group in this reaction. A rapid deprotection of substituted 2-bromobenzaldoximes afforded substituted 2-bromobenzaldehydes with good overall yields.


JOC, 2011. DOI: 10.1021/jo200853j

Synthesis of Carbolines by Photostimulated Cyclization of Anilinohalopyridines

A general synthetic route to prepare all four carboline regioisomers by photostimulated cyclization of anilinohalopyridines is described. The methodology affords various substituted carbolines in good to excellent yields. In the case of α-carbolines, the S_RN1 methodology complements previously reported palladium-catalyzed cyclization approaches.


Roberto A. Rossi, JOC, 2011, DOI: 10.1021/jo200923n

Tandem indole C–H alkenylation/arylation for tetra-substituted alkene synthesis

Alkynyl indoles undergo a novel sequence of Pd-catalysed indole C–H activation/alkyne carbopalladation/arylation, with diaryliodonium salts providing the aryl components. An array of functionalised indole alkenes have been prepared in good to excellent yield, with the reaction being selective for the Z-alkene.

Synthesis of Azaheterocycles from Aryl Ketone O-Acetyl Oximes and Internal Alkynes by Cu–Rh Bimetallic Relay Catalysts

A synthetic method for azaheterocycles from aryl ketone O-acetyl oximes and internal alkynes has been developed by using the Cu(OAc)₂–[Cp*RhCl₂]₂ bimetallic catalytic system. The reactions proceeded with both of anti- and syn-isomers of oximes with a wide scope of substituents. The Cu–Rh bimetallic system could be applied for the synthesis of isoquinolines as well as β-carboline, furo[2.3-c]pyridine, pyrrolo[2,3-c]pyridine, and thieno[2,3-c]pyridine derivatives.

Direct Michael Addition of Alkenes via a Cobalt-Dinitrosyl Mediated Vinylic C–H Functionalization Reaction

F. Dean Toste and Robert G. Bergman, JACS, 2011, DOI: 10.1021/ja204564z

Rational Catalysis Design on the Basis of Mechanistic Understanding: Highly Efficient Pd-Catalyzed Cyanation of Aryl Bromides with NaCN in Recyclable Solvents

Rational catalysis design on the basis of a detailed mechanistic understanding has been used to successfully develop the first efficient general Pd-catalyzed aromatic cyanation reaction under the highly sought after practicable conditions: (i) MCN (M = Na or K) as a cyanide source; (ii) low-boiling recyclable solvents; and (iii) minimal quantities of inexpensive, nontoxic promoters. The developed catalytic reaction converts aromatic bromides to the corresponding nitriles in 88–99% isolated yield with NaCN and 0.5–1.0 mol % of a t-Bu₃P-monoligated Pd catalyst in MeCN-THF within 2 h at 70 °C. The process exhibits high functional group tolerance.




Vladimir V. Grushin, JACS, DOI: 10.1021/ja2042035

Organogold Reactivity with Palladium, Nickel, and Rhodium: Transmetalation, Cross-Coupling, and Dual Catalysis

DOI: 10.1021/ar200055y

Recent advances in the gold-catalyzed additions to C–C multiple bonds

Abstract

C–O, C–N and C–C bonds are the most widespread types of bonds in nature, and are the cornerstone of most organic compounds, ranging from pharmaceuticals and agrochemicals to advanced materials and polymers. Cationic gold acts as a soft and carbophilic Lewis acid and is considered one of the most powerful activators of C–C multiple bonds. Consequently, gold-catalysis plays an important role in the development of new strategies to form these bonds in more convenient ways. In this review, we highlight recent advances in the gold-catalyzed chemistry of addition of X–H (X = O, N, C) bonds to C–C multiple bonds, tandem reactions, and asymmetric additions. This review covers gold-catalyzed organic reactions published from 2008 to the present.

Beilstein J. Org. Chem. 2011, 7, 897–936. doi:10.3762/bjoc.7.103

Chlorination and ortho-acetoxylation of 2-arylbenzoxazoles

Efficient and facile catalytic protocols for chlorination and ligand-directed ortho-acetoxylation of 2-arylbenzoxazoles have been developed. The chlorination is not a ligand-directed ortho-functionalization, but an electrophilic substitution process in the benzo ring of the benzoxazole moiety. Meanwhile, the acetoxylation exhibited high regioselectivity for the substrates containing a meta-substituent and occurred at the less sterically hindered ortho-C–H bond of the directing group.

Recyclable Copper Catalyst for meta-Selective CH Bond Arylation

It's a fair cop guvner: The meta-selective arylation of various anilides with diaryliodonium triflates was achieved by using copper oxide nanoparticles imbedded in aluminum oxyhydroxide, Cu/AlO(OH). The copper catalyst is much more reactive than homogeneous Cu^I and Cu^II catalysts; it is also recyclable.

1. Prof. Jaiwook Park, Chem. cat. Chem. 2011,  
DOI: 10.1002/cctc.201100072

Ruthenium-Catalyzed Oxidative Annulation by Cleavage of CH/NH Bonds

Bond activation in action: Unprecedented ruthenium-catalyzed oxidative annulations of alkynes through cleavage of CH bonds set the stage for an efficient 1(2H)-isoquinolone synthesis with ample scope (see scheme; tAm=tert-amyl). Mechanistic studies provided strong evidence for a rate-limiting CH bond metalation through carboxylate assistance.

1. Prof. Dr. Lutz Ackermann, Angew. Chem. Int Ed. 2011, 
DOI: 10.1002/anie.201101943