Palladium-catalyzed direct and regioselective C-H bond functionalization/oxidative acetoxylation of indoles.

The first general examples of palladium-catalyzed direct and selective oxidative C3-acetoxylation of indoles are presented. The mild reaction conditions (70 °C and with weak base, KOAc) in this indole C-H-acetoxylation are notable.

A general palladium catalyst system for Suzuki-Miyaura coupling of potassium aryltrifluoroborates and aryl mesylates.

The first general examples of palladium-catalyzed Suzuki-type cross-coupling of aryl and heteroaryl mesylates with potassium aryl and heteroaryltrifluoroborates are presented. In addition to biaryl couplings, the cross-coupling reactions of aryl mesylates with alkyl and vinyltrifluoroborate salts have also been successfully accomplished.

Suzuki-Miyaura coupling of aryl tosylates catalyzed by an array of indolyl phosphine-palladium catalysts.

A family of indolyl phosphine ligands was applied to Suzuki-Miyaura cross-coupling of aryl tosylates. Catalyst loading can be reduced to 0.2 mol % for coupling of nonactivated aryl tosylate. A challenging example for room temperature coupling is realized. The scope of this highly active Pd/L2 system can be extended to other boron nucleophiles, including trifluoroborate salts and boronate esters. The ligand structural comparisons toward the reactivity in tosylate couplings are also described.

A new family of tunable indolylphosphine ligands by one-pot assembly and their applications in Suzuki-Miyaura coupling of aryl chlorides.

This study describes a new class of indolylphosphine ligands, which can be easily accessed by a simple one-pot assembly from commercially available indoles, acid chlorides, and chlorophosphines. A combination of these three starting materials provides a high diversification of the ligand structure. The application of this ligand array in palladium-catalyzed Suzuki-Miyaura coupling reaction of aryl chlorides with arylboronic acids is described. A catalyst loading down to 0.01 mol % of Pd can be achieved.

Easily accessible and highly tunable indolyl phosphine ligands for Suzuki-Miyaura coupling of aryl chlorides.

This study describes a new class of easily accessible indolyl phosphine ligands, prepared via an efficient protocol involving Fischer indolization from readily available phenylhydrazine and substituted acetophenones. This versatile ligand scaffold provides beneficial features, including high potential of steric and electronic tunability. The air-stable indolyl phosphines in combination with a palladium metal precursor provide highly effective catalysts for Suzuki-Miyaura coupling of unactivated aryl chlorides, and the catalyst loading down to 0.02 mol % can be achieved.

An efficient palladium-benzimidazolyl phosphine complex for the Suzuki-Miyaura coupling of aryl mesylates: facile ligand synthesis and metal complex characterization.

A new class of easily accessible hemilabile benzimidazolyl phosphine ligands has been developed. The ligand skeleton is prepared from commercially available and inexpensive o-phenylenediamine and 2-bromobenzoic acid. With catalyst loading down to 0.5 mol% palladium, excellent catalytic activity towards the Suzuki-Miyaura coupling of aryl mesylates is still observed. This represents the lowest catalyst loading achieved so far for this reaction in general. X-Ray crystallography shows that new ligand L2 is coordinated with Pd in a κ(2)-P,N fashion.

A mild and efficient palladium-catalyzed cyanation of aryl chlorides with K4[Fe(CN)6].

An efficient palladium-catalyzed cyanation of aryl chlorides is established. In the presence of a highly effective Pd/CM-phos catalyst, cyanation of aryl chlorides proceeds at 70 °C in general, which is the mildest reaction temperature achieved so far for this process. Common functional groups such as keto, aldehyde, ester, nitrile and -NH(2), and heterocyclic coupling partners including N-H indoles are well tolerated. Moreover, a sterically hindered nonactivated ortho,ortho-disubstituted electrophile is shown to be a feasible coupling partner in cyanation.

A versatile palladium catalyst system for Suzuki-Miyaura coupling of alkenyl tosylates and mesylates.

A general and effective palladium system for Suzuki-Miyaura coupling of alkenyl electrophiles under mild reaction conditions is reported. With the Pd(OAc)(2)/CM-phos system, a variety of alkenyl tosylates are coupled well with ArB(OH)(2). Moreover, the first successful examples of using alkenyl mesylates in alkenylation are also described.

Dialkylamino cyclopentadienyl ruthenium(ii) complex-catalyzed alpha-alkylation of arylacetonitriles with primary alcohols.

Aminocyclopentadienyl ruthenium complexes, [(eta(5)-C(5)H(4)NMe(2))Ru(PPh(3))(2)(CH(3)CN)](+)BF(4)(-) and [(eta(5)-C(5)H(4)NEt(2))Ru(PPh(3))(2)(CH(3)CN)](+)BF(4)(-), are moderately active catalysts for alpha-alkylation of arylacetonitriles with primary alcohols; on the other hand, the analogous unsubstituted cyclopentadienyl ruthenium complex [(eta(5)-C(5)H(5))Ru(PPh(3))(2)(CH(3)CN)](+)BF(4)(-) shows very low catalytic activity. On the basis of experimental results and theoretical calculations, rationalization for the much higher catalytic activity of the aminocyclopentadienyl complexes over that of the unsubstituted Cp complex is provided. In the catalytic systems with the former, it is possible to regenerate the active solvento complexes via protonation of the metal hydride intermediates and subsequent ligand substitution; this process is, however, very nonfacile in the catalytic system with the latter.

Palladium-indolylphosphine-catalyzed Hiyama cross-coupling of aryl mesylates.

Aryl mesylates are found to be applicable as electrophiles in organosilicon-mediated coupling reactions. The catalyst system comprising 2 mol % of Pd(OAc)(2) and CM-phos supporting ligand is highly effective in catalyzing Hiyama cross-coupling of various aryl and heteroaryl mesylates. Interesting acid additive effects show that the presence of 0.25-0.50 equiv of acetic acid efficiently suppresses the mesylate decomposition and generally promotes the coupling product yields.

The lewis acidic ruthenium-complex-catalyzed addition of beta-diketones to alcohols and styrenes is in fact Brønsted acid catalyzed.

The perchlorate salt of the dicationic bipy-ruthenium complex cis-[Ru(6,6'-Cl2bipy)2(H2O)2]2+ effectively catalyzes addition of beta-diketones to secondary alcohols and styrenes to yield the alpha-alkylated beta-diketones. In a catalytic addition reaction of acetylacetone to 1-phenylethanol, the kappa2-acetylacetonate complex [Ru(6,6'-Cl2bipy)2(kappa2-acac)]ClO4 was isolated after the catalysis; this complex is readily synthesized by reacting cis-[Ru(6,6'-Cl2bipy)2(H2O)2](ClO4)2 with acetylacetone. [Ru(6,6'-Cl2bipy)2(kappa2-acac)]ClO4 is unreactive toward 1-phenylethanol in the presence of HClO4; it also fails to catalyze the addition of acetylacetone to 1-phenylethanol. On the basis of these observations, it is proposed and confirmed by independent experiments that the catalytic addition of beta-diketones to the secondary alcohols is in fact catalyzed by the Brønsted acid HClO4, which is generated by the reaction of cis-[Ru(6,6'-Cl2bipy)2(H2O)2](ClO4)2 with the beta-diketone.