Adriano L. Monteiro

Asymmetric hydrogenation of 2-arylacrylic acids catalyzed by immobilized Ru-BINAP complex in 1-n-butyl-3-methylimidazolium tetrafluoroborate molten salt

Abstract The [RuCl2-(S)-BINAP]2.NEt3 catalyst precursor dissolved in 1-n-butyl-3-methylimidazolium tetrafluoroborate molten salt is able to hydrogenate 2-arylacrylic acids (aryl=Ph or 6-MeO-naphthyl) with enantioselectivities similar or higher than those obtained in homogeneous media. Moreover, the hydrogenated products can be quantitatively separated from the reaction mixture and the recovered ionic liquid catalyst solution can be reused several times without any significant changes in the catalytic activity or selectivity.

PdCl2(SEt2)2 and Pd(OAc)2: simple and efficient catalyst precursors for the Suzuki cross-coupling reaction

Abstract PdCl 2 (SEt 2 ) 2 and Pd(OAc) 2 efficiently promote the cross-coupling of aryl bromides and chlorides with arylboronic acids under mild reaction conditions. These methods tolerate a variety of functional groups and represent, from a synthetic point of view, two of the simplest catalyst precursors that mediate the Suzuki cross-coupling reaction at room temperature.

On the use of phosphine-free PdCl2(SEt2)2 complex as catalyst precursor for the Heck reaction

A simple and efficient experimental protocol has been developed for the catalytic arylation of alkenes by the air and water stable, and phosphine-free compound PdCl2(SEt2)2 associated with tetrabutyl ammonium bromide. Using this catalytic protocol, aryl iodides and bromides, and electron-poor aryl chlorides are coupled with n-butylacrylate and styrene under relatively mild reaction conditions with high catalytic activity. Reaction vessel ultra-trace amounts (ppt) of this Pd precursor promotes the coupling of iodo benzene with n-butylacrylate with turnover numbers (mol product/mol Pd) up to 109.

Regioselective synthesis of 2-arylpropionic esters by palladium-catalyzed hydroesterification of styrene derivatives in molten salt media

Abstract 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 PdCl 2 (PhCN) 2 , (+)-neomenthyldiphenylphosphine (NMDPP) and p -toluenesulfonic acid under mild reaction conditions (10 atm and 70°C).

Charge-tagged acetate ligands as mass spectrometry probes for metal complexes investigations: applications in Suzuki and Heck phosphine-free reactions.

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).

Suzuki cross-coupling of aryl halides with aryl boronic acids catalyzed by phosphine-free NiCl2·6H2O

Abstract Aryl bromides and iodides can be coupled with phenylboronic acid in good yields using NiCl 2 ·6H 2 O as a catalyst precursor. This nickel complex is cheap, widely available and can be used without any auxiliary ligand or reducing agent.

Substitution of lead catalysts by zirconium in the oxidative polymerization of linseed oil

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.

Recent Progress in the Use of Pd-Catalyzed C-C Cross-Coupling Reactions in the Synthesis of Pharmaceutical Compounds

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.

Catalytic properties of Fe(acac)3 and Cu(acac)2 in the formation of urethane from a diisocyanate derivative and EtOH

Abstract 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 ).

Pd-catalyzed Suzuki cross-Coupling reaction of bromostilbene: insights on the nature of the boron Species

Arylboronate esters and arylborate salts can be used as partner for the Suzuki reaction of (E)-bromostilbene in the presence of Pd(OAc)2/PPh3 as catalyst precursor. While KOH is necessary for the coupling reaction with arylboronic acids and pinacol esters, aryl borate sodium salt can be used in a base-free protocol. The comparison between the three organoboron compounds using competitive experiments and electrospray ionization mass spectrometry analysis supports the proposition that the base initially reacts with the arylboronic acid or ester to form an arylborate species which undergoes the transmetallation process with the palladium catalyst.