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The Pd-catalyzed selective hydrogenation of C C double bond in (3,3-diphenylallyl)diisopropylamine or 3,3-diphenylallyl alcohol was evaluated using different catalytic systems [Pd/C, Pd(OAc)2/ionic liquid, isolated Pd(0) nanoparticles]. For the (3,3-diphenylallyl)diisopropylamine, hydrogenolysis is preferred over hydrogenation, and only moderate selectivities were obtained for the desired product. However, complete conversion and 100% selectivity were obtained for the hydrogenation of 3,3-diphenylallyl alcohol using isolated Pd(0) nanoparticles under mild condition. This successful strategy enabled the effective synthesis of diisopromine and feniprane drugs and opens new possibilities for the preparation of other biologically active compounds.

The Pd-catalyzed oxidative esterification of benzaldehyde with methanol using organic halides as oxidant agents is reported. Our results demonstrate the crucial role of the ligand in the choice of the oxidant for this reaction. Phenyl bromide can be used as oxidants by using dppp as ligand. On the other hand, benzyl bromide is much more selective when PPh 3 is used as the ligand. We were able to detect the key benzyl palladium intermediate in the catalytic cycle by using ESI-MS-(+). We also performed a one-pot C Br reduction/aldehyde oxidative esterification without the need for external oxidant agents.

The present study aimed to do an in-depth analysis of the effect of leaf scald on rice physiology by combining gas exchange measurements, photosynthetic pigment pools and examining the activities of enzymes involved in the antioxidant system. The size of leaf scald lesions increased from 3.1 mm at 24 h after inoculation (hai) to 25.2 mm at 120 hai. For the inoculated plants, net CO2 assimilation rate, stomatal conductance to water vapor and transpiration rate decreased while internal CO2 concentration increased in comparison to the not inoculated ones. The concentrations of chlorophyll a, chlorophyll b, total chlorophyll (a + b) and carotenoids decreased while the concentrations of malondialdehyde and hydrogen peroxide increased in the inoculated plants. The superoxide dismutase, ascorbate peroxidase, catalase, peroxidase and glutathione reductase activities significantly increased for the inoculated plants in comparison to non-inoculated ones. The results of this study show that infection by M. albencens negatively impacted the photosynthesis of rice leaves. Indeed, the CO2 fixation capacity was dramatically reduced during fungal infection, which was deeply associated with lower concentrations of photosynthetic pigments in a scenario where a more efficient antioxidative system was detrimental to remove reactive oxygen species generated over the course of fungal infection.

The Ts65Dn mouse is the most studied animal model of Down syndrome. Past research has shown a significant reduction in CA1 hippocampal long-term potentiation (LTP) induced by theta-burst stimulation (TBS), but not in LTP induced by high-frequency stimulation (HFS), in slices from Ts65Dn mice compared with euploid mouse-derived slices. Additionally, therapeutically relevant doses of the drug memantine were shown to rescue learning and memory deficits in Ts65Dn mice. Here, we observed that 1 μM memantine had no detectable effect on HFS-induced LTP in either Ts65Dn- or control-derived slices, but it rescued TBS-induced LTP in Ts65Dn-derived slices to control euploid levels. Then, we assessed LTP induced by four HFS (4xHFS) and found that this form of LTP was significantly depressed in Ts65Dn slices when compared with LTP in euploid control slices. Memantine, however, did not rescue this phenotype. Because 4xHFS-induced LTP had not yet been characterized in Ts65Dn mice, we also investigated the effects of picrotoxin, amyloid beta oligomers, and soluble recombinant human prion protein (rPrP) on this form of LTP. Whereas ≥10 μM picrotoxin increased LTP to control levels, it also caused seizure-like oscillations. Neither amyloid beta oligomers nor rPrP had any effect on 4xHFS-induced LTP in Ts65Dn-derived slices.

A critical overview is presented on the use of charged tagged ligands (CTLs) as immobilising agents in organometallic catalysis and as probes for studying mechanisms through electrospray ionisation mass spectrometry (ESI-MS) based on the most recent literature., In recent years, charge-tagged ligands (CTLs) have become valuable tools in organometallic catalysis. Insertion of an ionic side chain into the molecular skeleton of a known ligand has become a useful protocol for anchoring ligands, and consequently catalysts, in polar and ionic liquid phases. In addition, the insertion of a cationic moiety into a ligand is a powerful tool that can be used to detect reaction intermediates in organometallic catalysis through electrospray ionisation mass spectrometry (ESI-MS) experiments. The insertion of an ionic tag ensures the charge in the intermediates independently of the ESI-MS. For this reason, these ligands have been used as ionic probes in mechanistic studies for several catalytic reactions. Here, we summarise selected examples on the use of CTLs as immobilising agents in organometallic catalysis and as probes for studying mechanisms through ESI-MS.

This work shows the modification of microcrystalline cellulose by the selective oxidation of primary hydroxyl groups to carboxylate groups by a 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated system and its application as a heterogeneous ligand by ionic exchange with catalytic metals ions such as palladium, nickel and copper. Afterwards is described the application of the synthesized material as catalyst in coupling reactions such as Suzuki-Miyaura coupling and C−O bond formation reaction in different conditions, which are of great importance for the synthesis of drugs, natural products and new materials such as dendrimers, liquid crystals and polymers with magnetic and optical properties. The carboxyl cellulose matrix shows to have superior catalytic results as a ligand for all coupling reactions. Can be also highlighted the affinity of the carboxyl cellulose ligand in polar solvents such as water and alcohols and its application in mild conditions.

The Coordination for the Improvement of High Education Personnel (CAPES), the Brazilian federal agency for graduate programs, plays a fundamental role for the expansion and consolidation of the National Postgraduate System (SNPG) and the execution of the National Graduate Plan (PNPG) 2011-2020. In this paper, we discuss the evolution of the Brazilian graduate program in chemistry and its role in the formation of highly qualified professionals in chemistry (academic master’s degree, professional master’s degree and doctoral degree) for the academy, teachers and lecturers for all levels of the education system, as well for the non-academic market.

Made available in DSpace on 2018-11-26T17:39:54Z (GMT). No. of bitstreams: 0 Previous issue date: 2017-07-01. Added 1 bitstream(s) on 2021-07-15T14:32:05Z : No. of bitstreams: 1 S0100-40422017000600618.pdf: 1282913 bytes, checksum: a614e6356544402ba432f9275e8c7da8 (MD5) The Coordination for the Improvement of High Education Personnel (CAPES), the Brazilian federal agency for graduate programs, plays a fundamental role for the expansion and consolidation of the National Postgraduate System (SNPG) and the execution of the National Graduate Plan (PNPG) 2011-2020. In this paper, we discuss the evolution of the Brazilian graduate program in chemistry and its role in the formation of highly qualified professionals in chemistry (academic master's degree, professional master's degree and doctoral degree) for the academy, teachers and lecturers for all levels of the education system, as well for the non-academic market. Univ Fed Rio Grande do Sul, Inst Quim, Dept Quim Organ, Ave Bento Goncalves 9500,CP 15003, BR-91501970 Porto Alegre, RS, Brazil Univ Estadual Paulista, Inst Quim, Dept Quim Organ, Ave Prof Francisco Degni 55,CP 35, BR-14800900 Araraquara, SP, Brazil Univ Brasilia, Inst Quim, Campus Univ Darcy Ribeiro,CP 4478, BR-70904970 Brasilia, DF, Brazil Univ Estadual Paulista, Inst Quim, Dept Quim Organ, Ave Prof Francisco Degni 55,CP 35, BR-14800900 Araraquara, SP, Brazil

Cardiopulmonary bypass (CPB) is often associated with renal dysfunction, as measured by plasma creatinine levels and hemodialysis rates. Aim. To compare creatinine clearance (CrCl), estimated with the Cockroft and Gault formula, between patients undergoing off-pump coronary artery bypass grafting (OPCAB) versus on-pump CABG (on-CAB). Material and methods. Between April 2008 and April 2009, 119 patients underwent coronary bypass graft surgery. Fifty-eight (58) of these patients underwent OPCAB while 61 had on-CAB. Creatinine clearance, plasma creatinine levels, and clinical outcome were compared between the groups. A creatinine clearance value of 50 mL/minute was accepted as the lowest limit of normal renal function. Results. There were two hospital deaths caused by sepses after pulmonary infection. Creatinine clearance (Preoperative OPCAB 73,64±33,72 x on-CAB 75,70±34,30mL/min; discharge OPCAB 75,73±35,07 x on-CAB 79,07±34,71 mL/ min; p=0,609), and creatinine levels (Preoperative OPCAB 1,04±0,38 x on-CAB 1,13±0,53 mg/dL; discharge OPCAB 1,12±0,79 x on-CAB 1,04±0,29mg/dL; p=0,407) did not show statistically inter-group differences. Conclusion. Deterioration in renal function is associated with higher rates of postoperative complications. No significant difference in CrCl could be demonstrated between the groups.

In this work we describe the regio and stereoselective synthesis of (E)-3,3-diaryl and (E)-3-aryl-3-aryloxy allylamines and allylalcohols. The starting materials are the non-expensive commercially available cinnamyl alcohol and chloride. The bromination/dehydrobromination sequence furnished the (E)-3-bromo-3-phenylallyl amines and alcohol as single regioisomers and with high stereoselectivity (>98%). These vinyl bromides were used as substrates in cross-coupling reactions furnishing the arylated products with good to excellent yields and total E-configuration retention. With this protocol, we were able to produce regio and stereospecifically trisubstituted olefins and vinyl ethers by Suzuki cross-coupling and Ullmann vinylation.

The present work describes the synthesis of mono- and bis-pyrazole compounds bearing flexible p-tolyl ether and rigid 4,5-dibromo-2,7-di-tert-butyl-9,9-dimethyl-9H-xanthene backbones as pyrazolyl analogues of DPEphos and Xantphos ligands, respectively. The synthesis of new pyrazolyl analogues was accomplished following an Ullmann coupling protocol, and the resulting products were isolated in overall good yields. In addition, a hybrid imidazolyl−pyrazolyl analogue bearing a xanthene backbone was synthesized using the same protocol, whereas a hybrid selanyl−pyrazolyl analogue with a xanthene backbone was synthesized in a good yield employing a second C−H activation step. The symmetrical bis-pyrazolyl and the hybrid imidazolyl−pyrazolyl analogues were found to be the most active among the new ligands evaluated in the Pd-catalysed Suzuki-Miyaura cross-coupling of aryl halides with aryl boronic acids. A simple catalytic system based on Pd(OAc)2/2a was developed, which efficiently catalyses the Suzuki−Miyaura reaction of aryl halides and aryl boronic acids and provides moderate to excellent yields of the corresponding cross-coupling products.

Palladium and palladium-gold containing siliceous-MCM-41 and sol–gel palladium and palladium-gold silica composites have been prepared. The catalytic performance of incorporated Pd/MCM-41, Au-Pd/MCM-41 and Pd and Au-Pd/SiO2 sol–gel catalysts for the Suzuki–Miyaura cross-coupling reaction was determined and the influence of the matrix and the catalyst composition on the catalytic activity were also studied. The catalysts were characterized by N2 physisorption (BET/BJH methods), X-ray diffraction, temperature programmed reduction analysis, H2 chemisorption, atomic absorption spectrophotometry and Raman spectroscopy. The silica-containing palladium and palladium-gold catalysts prepared using the MCM-41 matrix showed greater catalytic activity than using the conventional sol–gel method; however, gold had a significant influence on this reaction. The catalyst did not undergo metal leaching and could be easily recovered and re-used (reused).

This work reports the functionalization of monoterpenoids with 2-iodo-1-methyl-1 H -imidazole using Sonogashira cross-coupling reactions. Natural monoterpenes were also modified to obtain­ the corresponding alkynes which were used in the cross-coupling­ step. After a sequence of cross-coupling–hydrogenation–N-alkylation–ion metathesis, novel ionic liquids were obtained in reasonable yields. The obtained products can be used as scaffolds for the further synthesis of new ionic liquids derived from terpenoids and for new, potentially bioactive materials, e.g. polycyclic monocationic scaffolds. All obtained products show the characteristics of a room temperature ionic liquid (RTIL).

A system based on copper/1,10-phenanthroline efficiently promotes the coupling between phenols or pyrazole with (E)-bromostilbene. (E)-1-Aryloxy-1,2-diphenylethenes were obtained from the coupling with phenols in good to excellent yields (69–90%). The exception was the reaction involving a phenol containing an electron-withdrawing cyano group that required a longer reaction time and gave only 49% yield. Kinetic studies indicated the participation of the vinyl halide in the rate-determining step. Under the conditions employed, the activation of the vinyl halide via a radical pathway was discarded using a radical scavenger test. By using an ionically-tagged 1,10-phenanthroline derivative as the ligand, various copper-based ions were detected through ESI(+)-MS. These ions suggested that formation of the active species [phenCuOAr(HOAr)2] precedes the vinyl halide activation.

An acetate anion bearing an imidazolium cation as its charge tag was reacted with M(OAc)(2) complexes (where M = Ni, Cu, and Pd; in situ reaction) to form members of a new class of charge-tagged metal complexes. The formation of these unprecedented precatalysts with potential for cross-coupling reactions was confirmed by electrospray ionization (and tandem) mass spectrometry. The catalytic performance of the palladium complex was tested in Heck and Suzuki cross-coupling reactions, often with superior activity and yields as compared with Pd(OAc)(2).

We present in this work a comprehensive investigation of the role played by dissolved tetrafluoroboric acid on the electrochemical response of a polycrystalline platinum electrode in acidic media. HBF4 from two different suppliers was employed and characterized in terms of the amount of arsenic contamination by Inductively Coupled Plasma-Optical Emission Spectroscopy. The effect of different amounts of HBF4 on the voltammetric profile of the Pt|HClO4(aq) interface was investigated by means of electrochemical quartz crystal nanobalance (EQCN). Despite the comparable cyclic voltammograms, the presence of arsenic in one of the two HBF4 used resulted in dramatic variations in the mass change profile, which evidences the deposition/dissolution of arsenic prior to the surface oxidation. For the arsenic-free HBF4, its effect on the mass change profile was mainly associated to anion adsorption. The impact of dissolved HBF4 on the electro-oxidation of formic acid was rationalized in terms of two contributions: current enhancement at low potentials due to the arsenic-assisted formic acid electro-oxidation and inhibition at high potentials due to anion adsorption.

We have developed a sequential and selective Pd-catalyzed double-Heck arylation of ethylene that results in non-symmetrical nitro-stilbene analogs of trans-resveratrol at excellent yields. A catalytic system consisting of Pd(OAc)2 and P(o-tolyl)3 permitted us to carry out the two consecutive Heck arylations without losing activity from the first to the second Heck reaction. After the first Heck arylation of ethylene, no isolation or additional catalyst loading is required for the second Heck arylation reaction. This protocol was applied to the synthesis of methylated trans-resveratrol, which was obtained at a 65% overall yield. Copyright © 2011 John Wiley & Sons, Ltd.

Instead of a time-invariant voltammetric profile, many electrochemical systems display a cycledependent current–potential response. This phenomenon has been referred to as complex voltammetric response and it has been observed during the electro-oxidation of several molecules such as methanol, ethanol, propanol and hydrogen. There are currently two explanations for the surface mechanism underlying this behavior. In one scenario, the complex voltammogram would result from the specific kinetic pathway taken during the forward sweep. In the other explanation, the phenomenon is discussed in terms of the interplay among the surface roughening and subsequent relaxation, and the ohmic drop coupled to a negative differential resistance. We report in this paper a nanogravimetric investigation of the complex voltammetric response in the electro-oxidation of methanol on platinum electrode in both acidic and alkaline media. Different periodic patterns composed of intercalated small and large hysteresis cycles were observed as a function of the applied voltage and the series resistance between the working electrode and the potentiostat. Independently, nanogravimetric results indicated no detectable difference in the delta-frequency versus voltage profile between small and large hysteresis cycles. These findings were interpreted as experimental evidence of the secondary, if any, role played by the very electrochemical reaction on the emergence of complex voltammetric response.

The complexes formed by combining Pd(OAc)2 and iminophosphine ligands (P^N) are active catalysts in Suzuki–Miyaura cross-coupling reactions under mild conditions. Aryl bromides and iodides, as well as benzyl chlorides give the corresponding coupled products in high yields at low temperatures (25–50 °C) using these catalysts. Iminophosphines containing the most sterically demanding groups attached to the N-imino moiety were the most effective ligands. New divalent Pd complexes of known iminophosphines were synthesised and their activity was compared with the in situ generated catalyst system. The complex resulting from the oxidative addition of 4-bromo anisole [Pd(4-CH3OC6H4)Br(P^N)] was more active than the in situ generated system. However, palladacycles containing the iminophosphine ligand (e.g., {[C6H4CH(Me)2St-Bu]Pd(P^N)}+PF6−) were less active than the in situ generated catalyst due to the greater stability of the complexes that involve two bidentate ligands. Poisoning tests demonstrated that homogeneous mononuclear palladium species containing the iminophsophine ligand were responsible for the catalytic activity.

The reaction of [PdCl(Me)(cod)] (cod = 1,5-cyclooctadiene) with tridentate bis(pyrazolyl) ligands affords the alkyl-palladium(II) complexes [Pd(CH 3 )(NZN)][BF 4 ] ( 1 , NZN = 1,1′-(2,2′-oxybis(ethane-2,1-diyl)bis(3,5-dimethyl-1H-pyrazole); 2 , NZN = bis[2-(3,5-dimethyl-1H-pyrazol-1-yl)ethyl]sulfane) in good yield. Compounds 1 – 2 were characterized by elemental analysis, multinuclear NMR spectroscopy, and X-ray structural analysis. Single crystal X-ray structural analyses indicate that the complexes are monomeric and the palladium center resides in a slightly distorted square planar environment. Furthermore, despite their intrinsic similarity, the NON and NSN ligands adopt different coordination modes around the palladium metal center. Additionally, the [PdCl 2 (NON)] ( 3 ) was shown to be an efficient catalyst precursor for the coupling of aryl bromides and iodides with arylboronic acids, esters and borate salts.

( Z)-Tamoxifen was synthesized froma simple olefin ( TRANS-stilbene) in 5steps and 40% overall yield ( Z/ E = 74:26).The phenyl substituted group (4-Me 2 NCH 2 CH 2 OC 6 H 4 )was attached by a bromination-dehydrobromination-Suzukireaction sequence. Subsequently, the ethyl group was attached tothe triarylated olefin by a bromination-Negishi reactionsequence. Both the Suzuki and Negishi cross-coupling processes arestereospecific, and the stereoselectivity depends only on the bromination-dehydrobromination reactions.( Z)-Tamoxifen was also obtained from TRANS-stilbene in only 3 steps by usingHeck reaction-bromination-Negishi reaction sequencein 57% overall yield ( Z/ E = 65:35).

The reaction of glycerol with phenylboronic acid provided a mixture of cyclic glycerol esters, glycerol 1,2-phenylboronate (80%), and glycerol 1,3-phenylboronate (20%). The latter two products were formed from the esterification of the 1,2- and 1,3-hydroxyl groups, respectively. The glycerol phenylboronates were applied to the Pd-catalyzed Suzuki cross-coupling reactions with aryl halides, affording the corresponding biphenyl products in high yields. Excess glycerol phenylboronate was not required, and the Suzuki coupling reaction employed a simple catalyst precursor prepared in situ from palladium acetate and triphenylphosphine under mild reaction conditions. Arylboronic acid and pinacol arylboronic ester yielded similar results under the optimized reaction protocol.

Air-stable cyclopalladated compounds derived from the ortho-metalation of benzylic tert -butyl thioethers efficiently promote C–C coupling reactions and were studied mechanistically in the Suzuki reaction. The catalytic reaction was monitored by 19 F NMR and GC–MS and the decomposition of the S-palladacycle was studied under stoichiometric conditions, showing that these palladacycles serve as a reservoir of zerovalent palladium species. The formation of these species is initiated by attack of the arylboronic acid on the palladacycle resulting in the formation of an arylated palladacycle. Thereafter, this species undergoes a reductive elimination to form the active Pd(0) species. As a minor pathway, the Pd(0) species could also be generated in a pathway involving a reduction process that leads to the decomposition of the palladacycle to Pd(0) affording the ortho hydrogenated thioether. Poisoning studies and TEM analysis indicated the presence of palladium nanoparticles. Competitive experiments showed that electron-withdrawing substituents on the aryl halide and electron-donating substituents on the arylboronic acid facilitated the reaction. They also provide evidence that the soluble species formed from the oxidative addition, that are active for Heck and Suzuki reactions, are the same species.

The electrocatalytic reduction of NO 3 - (aq) over platinum has been investigated in sulfuric acid solutions with proton concentrations between 1 mM and 50 mM. Cyclic voltammetry indicates that for [H+] NO 3 - (aq) is reduced in two distinct regions of potential: one reduction peak occurs at approximately 0.1 V vs. RHE and one occurs at −0.13 V vs. RHE. This second reduction peak has never before been observed, and is not present for proton concentrations >10 mM, where hydrogen electroreduction prevails below 0.0 V vs. RHE. Chronoamperometry shows that the kinetics of the two reduction peaks are distinct, suggesting that the two reduction peaks may correspond to the evolution of different products. Results are discussed in the context of tuning the product selectivity of the electrocatalytic reduction of NO 3 - (aq).

A catalyst precursor prepared in situ from palladium acetate and a phosphine ligand was used for the Stille cross-coupling reaction of benzylic bromides and chlorides with aryltributyltin analogues. The reactions were performed at 80 °C using dppf as ligand in the presence of KF, or more conveniently using PPh 3 in the absence of base, furnishing diarylmethane derivatives in high yields (86–99%). Using Pd(OAc) 2 /PPh 3 as catalyst precursor competitive Stille and Suzuki cross-coupling reactions with benzyl chloride showed that in the absence of base or in the presence of KF the Stille product is the majority product, and only the Suzuki product was obtained in the presence of KOH as base.

The impressive ability of palladium to assemble C-C bonds between appropriately functionalized substrates has allowed synthetic organic chemists to perform transformations that were previously impossible or only possible using multi-step approaches. In this context, one of the most important and elegant applications of the Pd-catalyzed C-C coupling reactions currently is the synthesis of pharmaceuticals. This review is intended to give a picture of the applications of Pd-catalyzed C-C cross-coupling reactions for the synthesis of drug components or drug candidates regardless of the scale from 2011 through to the end of July, 2014.

Vinyl bromides (I) are used as substrates in cross-coupling reactions furnishing arylated products (III) and (V) in good to excellent yields and complete retention of the (E)-configuration.

The reaction of phosphinite Me2NCH2C C(CH2)2OP(i-Pr)2 (2) with Li2PdCl4 in methanol at room temperature affords the air and water stable mixed pincer palladacycle (Me2NCH2(Cl)C C(CH2)2OP(i-Pr)2-κNκCκP)PdCl (3) whose structure has been ascertained by means of an X-ray diffraction study. This pincer palladacycle is a highly efficient catalyst precursor for the coupling of aryl boronic acids and aryl chlorides. Both electron-rich and -poor aryl chlorides are efficiently coupled in the presence of 3 to furnish the corresponding cross-coupled products in excellent yields, and a wide variety of functional groups are tolerated in both aryl chloride and aryl boronic acid. The experimental protocol has also been extended for the coupling of iodo and bromo arenes with aryl boronic acids for the generation of hindered biphenyls. The coupling process afforded very good yields of biphenyl products containing two ortho substituents. Steric hindrance is more sensitive for ortho substituents in the aryl boronic acid and is more pronounced when the coupling reaction involves three ortho substituents.

(1,2-Dibromomoethyl)arenes, obtained from the bromination of styrene derivatives were regioselectivley dehydrobrominated to α-arylvinyl bromides in very good yields (82–94%). The vinyl bromides generated in situ underwent palladium-catalyzed carbonylation furnishing 2-arylacrylic esters, which are precursors for non-steroidal anti-inflammatory drugs. The best catalytic system is composed of PdCl2(PPh3)2 (0.5–2 mol%), PPh3 as phosphine ligand and iPrEtN as base. The carbonylation reaction can be carried out under mild conditions (10 atm of CO, 100 °C, 3.5 h) affording the esters in very good yields (88–95%). Moreover, we have developed a one-pot deydrobromination/carbonylation procedure.

The impressive ability of palladium to assemble C-C bonds between appropriately functionalized substrates has allowed synthetic organic chemists to perform transformations that were previously impossible or only possible using multi-step approaches. In this context, one of the most important and elegant applications of the Pd-catalyzed C-C coupling reactions currently is the synthesis of pharmaceuticals. This review is intended to give a picture of the applications of Pd-catalyzed C-C cross-coupling reactions for the synthesis of drug components or drug candidates regardless of the scale from 2011 through to the end of July, 2014. A grande capacidade do paládio de formar ligações carbono-carbono entre substratos apropriadamente funcionalizados permitiu que os químicos orgânicos efetuassem transformações antes impossíveis ou alcançáveis somente através de rotas muito longas. Neste contexto, uma das mais elegantes e importantes aplicações das reações de acoplamento cruzado catalisadas por paládio é a síntese de compostos de interesse farmacêutico. A presente revisão tem por objetivo apresentar uma visão geral do uso de acoplamentos cruzados na síntese de componentes de medicamentos (ou de candidatos a medicamentos), independentemente da escala, compreendendo o período de 2011 até o final de julho de 2014.

The C−H activation of C-3-unsubstituted 1,4-benzodiazepin-2(3H)-ones (LH = 2a−c) (2a = 1-methyl-5-phenyl-1H-1,4-benzodiazepin-2(3H)-one, 2b = 1-benzyl-5-phenyl-1H-1,4-benzodiazepin-2(3H)-one, 2c = benzyl-2-(2,3-dihydro-2-oxo-5-phenyl-1,4-benzodiazepin-1-yl)acetate) with Na2PdCl4 afforded the insoluble palladacycles [(L)PdCl]2 3a−c. Treatment of the latter with triphenylphosphine afforded the soluble monomeric triphenylphosphine analogues [(L)Pd(PPh3)Cl] 4a−c. 1-Methyl-3-(2-(methylthio)ethyl)-5-phenyl-1H-1,4-benzodiazepin-2(3H)-one (LH = 2d) reacted with Na2PdCl4 or with PdCl2(MeCN)2 to afford the monomeric cis-S−N-coordinated complex 5d of the type [(LH)PdCl2]. 3-((tert-Butylthio)methyl)-1-methyl-5-phenyl-1H-1,4-benzodiazepin-2(3H)-one, 2e, reacted with Pd(OAc)2 in acetic acid and, following LiCl metathesis, yielded the monomeric cis-S−N-bound pincer palladacycle 6f. X-ray structures of 5d and 4a have been determined. 3a and 6f were found to be effective precatalysts for Suzuki coupling reactions, and 3a,...

A simple catalyst precursor prepared in situ from palladium acetate and triphenylphosphine shows high activity for the Suzuki cross-coupling reaction of benzylic bromides and chlorides with aryl boronic acids. The reaction can be carried out at low catalyst loading (0.002–1 mol%) and under mild conditions (room temperature to 80 °C) furnishing diarylmethane derivatives in high yields (86–99%).

The oxidative addition of benzyl chloride to Ni(cod) 2 in the presence of 1,4-bis(2,6-diisopropylphenyl)acenaphthenediimine followed by chloride abstraction affords [(η 3 -CH 2 C 6 H 5 )Ni(α-diimine)][PF 6 ](α-diimine=1,4-bis(2,6-diisopropylphenyl)acenaphthenediimine) in 70% yield. The complex is active in ethylene polymerization in the presence of methylaluminoxane and under mild reaction conditions. The polyethylenes obtained are highly branched, have very low densities, do not show T m or measurable crystallinity and have molecular weights ranging from 80 x 10 3 to 290 x 10 3 g.mol -1 .

The 1,3-enyne is an important core structure often found in many naturally occurring and biologically active compounds. In addition, 1,3-enynes are also very useful synthetic intermediates. The Pdcatalyzed Sonogashira reaction is one of the most powerful methods for the synthesis of such compounds. Pd complexes containing phosphine ligands associated with copper(I) iodide are the most widely used catalysts for this reaction. In the past several years, some protocols using copper catalysts have been developed. Recently, we have shown that a catalytic system based on CuI/1,10phenanthroline efficiently promotes the coupling between phenols or pyrazole with (E)bromostilbene. Here we present our first results about the coupling of vinyl bromides with alkynes.

Racemic sulfur chloro-bridged palladacycles (rac-4b−6b), derived from the orthopalladation of (1-tert-butylsulfanylethyl)benzene, (1-methylsulfanylethyl)benzene, and 2-(1-tert-butylsulfanylethyl)naphthalene (rac-1−3), have been synthesized in good yields using palladium acetate as the metalation agent and followed by reaction with LiCl. Palladacycles rac-4b and rac-6b have been isolated as single isomers, whereas rac-5b has been obtained as a mixture of two diastereoisomers (3:1). Variable-temperature 1H NMR showed that the S-t-Bu palladacycle 4b is configurationally stable over a large range of temperatures (from −20 to 100 °C). On the other hand, S-Me analogue 5b undergoes facile sulfur pyramidal inversion with an energy barrier of 18 kcal/mol. Moreover, the optically active (1-alkylsufanylethyl)benzenes, (R)-1 and (R)-2, respectively, have been prepared in 91% and 97% ee, respectively, from the reaction of sodium methylthiolate and sodium tert-butylthiolate, respectively, with non-racemic (S)-(−)-1-phe...

The hydrovinylation of arylethylenes catalyzed by [Ni(MeCN)6][BF4]2/AlEt2Cl/PPh3 was modulated to obtain 3-aryl-1-butenes in high yields and selectivities. A wide variety of arylethylenes containing electron-donating or electron-withdrawing groups and Lewis basic group, can be hydrovinylated at room temperature and under mild conditions by changing the relative ratios of the three-component catalyst. Similar activities and selectivities were observed for o-, m- and p-substituted styrenes. Also, the hydrovinylation of olefins with substituents in the vinyl fragment, such as α-methylstyrene and indene, can be accomplished.

The effect of the nature of alcohol, namely ethanol (EtOH), hydroxyethyl propionate (EPOH) and 2-hydroxypropyl propionate (PPOH), on the catalytic properties of Fe(acac) 3 and Cu(acac) 2 is evaluated in the formation of mono- and diurethanes from hexamethylenediisocyanate (HDI). The highest turnover rate,77 h −1 , was observed with the reaction between HDI and PPOH catalysed by Fe(acac) 3 , which also afforded a diurethane selectivity of 100%. Similar experiments conducted with a commercial catalyst, dibutyltin dilaurate (DBTDL), show that for the same reaction conditions, no diurethane adduct is formed and that the turnover rate is lower (19 h −1 ). A discussion concerning the probable active species is made in order to explain the activity, kinetic and selectivity results.

In this study, the oxidation of linseed oil was used as a model for oxidative alkyd paint system. A comparative study between cobalt, lead and zirconium octoates as catalysts for oxidative polymerization of linseed oil has been performed. The cobalt salt catalyzes the oxidation step, and the lead and zirconium catalyze the polymerization step. Under the same reaction conditions, the zirconium catalyst is more efficient than lead. As the use of lead compounds is associated with toxicological problems, our results suggest use of the zirconium salt as a substitute for lead compounds in industrial applications.

Catalytic carbonylation of benzylic esters, ethers or alcohols in the presence of [Pd(PPh3)2Cl2] and HBF4·OEt2 as co-catalyst affords 3-phenylpropionic acid or esters with good yields and selectivities. It is shown that the reaction proceeds smoothly in methanol through the intermediary of the corresponding 1-phenylethyl methyl ether.

The palladium-catalyzed hydroesterification of styrene derivatives is performed in a two-phase system composed of 1-n-butyl-3-methylimidazoliumtetrafluoroborate salt (ionic phase) and isopropanol/cyclohexane (organic phase). Very high regioselectivities in 2-arylpropionic esters (≥99.5%) are obtained using a catalytic system composed of PdCl2(PhCN)2, (+)-neomenthyldiphenylphosphine (NMDPP) and p-toluenesulfonic acid under mild reaction conditions (10 atm and 70°C).

The catalytic performance of metal– β -diketone complexes Fe(acac) 3 and Cu(acac) 2 is described for urethane formation reactions from hexamethylene diisocyanate (HDI) and ethanol. This is a model reaction for the synthesis of polyurethane resin that takes place during the application of reactive paint. The best results are obtained for the reaction between HDI and EtOH catalysed by the Fe(acac) 3 complex. The diurethane adduct selectivity is 90% with a turnover rate of 74 h −1 . Similar experiments conducted with a commercial catalyst, dibutyltin dilaurate (DBTDL), show that for the same reaction conditions no diurethane adduct is formed and that the turnover rate is lower (29 h −1 ).

The PR 3 –CS 2 adduct displays an unusual promoting effect on the activity of butene oligomerization catalyzed by nickel complexes in biphasic dialkylimidazolium organochloroaluminate ionic liquid (IL) systems. The promoting effect on the activity was studied and was found to be dependent on the nature of the anionic aluminum species present on the IL, making it observable only in acid ILs.

Ionic liquids (ILs) are regarded as a great media for organometallic catalysis. It has been recently reviewed that the use of modified catalysts, which incorporate an ionic tag such as the imidazolium ring, may comprise a promising solution for the problem of catalyst leaching. 1 In this sense, we describe herein a novel ionically-tagged palladium catalyst and its application in C-C bond formation.

In the past years significant improvements were achieved for the copper-catalyzed C-O and C-N coupling reactions 1 . The use of appropriate ligands allowed the efficiently coupling reaction under mild conditions and low catalyst loadings. Therefore, important building blocks of organic synthesis can be selectively produced. In this context vinylethers and vinylamines can be easily obtained through the coupling of phenols/azoles with vinyl halides. In present work, we performed the coupling of substituted phenols and azoles with (E)bromostilbene and bromotriphenylethene using a simple catalytic system composed by CuI and phenantroline. By using this protocol we were able to produce triand tetra-substituted vinylethers and vinylamines in good to excellent yields (Scheme 1).