[show abstract][hide abstract] ABSTRACT: This review describes the recent advancement of transition metal-catalyzed aromatic carbon-boron bond construction processes. The efficacy of palladium, nickel and copper catalysis are comparatively illustrated. Particular focus is placed on the application of ligands, for instance tailor-made phosphines and carbenes that can effectively enable the borylation of challenging and sterically demanding substrates. Selected applications of this methodology for the synthesis of pharmaceutically useful and materially interesting molecules are mostly documented. This review includes literatures up to late 2012.
[show abstract][hide abstract] ABSTRACT: This study reports the first general Pd-catalyzed direct arylation of polyfluoroarenes with aryl tosylates/mesylates. A wide range of polyfluoroarenes can be coupled with both aryl tosylates and mesylates under relatively mild reaction conditions (90 °C, in the presence of a weak base KOAc, without any additional acid additives). Moreover, a one-pot sequential C–H bond functionalization/C–N bond coupling has been successfully accomplished by employing one single Pd/CM-phos catalyst system.
[show abstract][hide abstract] ABSTRACT: This study describes the efficacy of P,N-type benzimidazolyl phosphine ligands, which can be easily synthesized from commercially available and inexpensive starting materials. The application of this ligand array in palladium-catalyzed Suzuki–Miyaura coupling reaction of aryl chlorides with potassium aryltrifluoroborates is described. The air stable benzimidazolyl phosphines in combination with a palladium metal precursor provides highly effective catalysts for the Suzuki–Miyaura coupling of unactivated aryl chlorides and can achieve a catalyst loading of only 0.05 mol %.
[show abstract][hide abstract] ABSTRACT: 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.
Chemical Communications 02/2012; 48(14):1967-9. · 6.38 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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.
Chemical Communications 06/2011; 47(29):8328-30. · 6.38 Impact Factor
[show abstract][hide abstract] ABSTRACT: The hydro(trispyrazolyl)borato-ruthenium(II) diphosphinoamino complex TpRu[4-CF3C6H4N(PPh2)2](OTf) (I) [Tp=hydro(trispyrazolyl)borate] catalyzes the Markovnikov addition of β-diketones to unactivated 1-alkynes in good to excellent yields. The reaction proceeds under solvent-free and additive-free conditions and the catalyst loading can be reduced down to 0.4 mol%. Complex I (1 mol%) also catalyzes the addition of secondary amines to aromatic terminal alkynes, unusual anti-Markovnikov products are exclusively formed.
[show abstract][hide abstract] ABSTRACT: 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.
[show abstract][hide abstract] ABSTRACT: 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.
The Journal of Organic Chemistry 01/2011; 76(1):80-4. · 4.56 Impact Factor
[show abstract][hide abstract] ABSTRACT: 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.
The Journal of Organic Chemistry 08/2010; 75(15):5109-12. · 4.56 Impact Factor
[show abstract][hide abstract] ABSTRACT: Aminocyclopentadienyl ruthenium complexes, [(η5-C5H4NMe2)Ru(PPh3)2(CH3CN)]+BF4− and [(η5-C5H4NEt2)Ru(PPh3)2(CH3CN)]+BF4−, are moderately active catalysts for α-alkylation of arylacetonitriles with primary alcohols; on the other hand, the analogous unsubstituted cyclopentadienyl ruthenium complex [(η5-C5H5)Ru(PPh3)2(CH3CN)]+BF4− 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.
[show abstract][hide abstract] ABSTRACT: 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.