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1

Synteza γ-laktonów z podstawnikami aromatycznymi

Skrobiszewski A., Gładkowski W.

Wiadomości Chemiczne

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2013

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[Z] 67, 9-10

943--960

EN

Biological activities of lactones are predominantly determined by different substituents on a lactone ring. γ-Lactones with aromatic substituents have interesting biological activities and serve as useful intermediates in the synthesis of many natural and synthetic products. Pulvinic and vulpinic acids exhibit antimicrobial, antioxidant and anticancer activity [1–3]. Paraconic acids have anticancer and antibacterial activity [4, 5]. The interesting biological activities i.a. antileukemic, anti- HIV and cytostatic, have been found for dibenzyl-γ-lactones [8]. This review covers some examples of synthetic and biotechnological methods leading to either racemic or optically active γ-lactones with aromatic substituents. The racemic α-benzylidene lactones can be produced from Baylis-Hillman acetates [9]. The multicomponent synthesis of the paraconic acid analogs is performed by a fourfold metallation-conjugate addition-aldol addition-intramolecular transesterification sequence [4]. Suzuki-Miyaura reaction is the key step in the synthesis of asymmetric pulvinic acids [1]. Some other examples of synthetic strategies involving the reactivity of ylides, vicinal dianions, ozonolysis or Claisen rearrangement are also presented [10–13]. Production of optically active γ-lactones with aromatic substituents involves application of biotechnological and chemical methods. The first one includes using commercially available enzymes [16, 17] or whole cells of microorganisms [18–20]. Chemical methods involve application of chiral starting materials like malic acid esters or the derivatives of succinic acid [14, 15] or chiral catalysts like BINAP-Rh or Ru complexes [7].

2

Synteza liganda Sym-Phos {dicykloheksylo[3-(2,4,6-trimetoksyfenylo)-4-metoksynaft-2-yl]fosfina} i jego zastosowanie w reakcji Suzuki-Miyaura

Kielar K., Demchuk O. M.

Chemik

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2012

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Vol. 66, nr 6

585-594

PL

Przedstawiono tanią, szybką oraz wydajną trzyetapową syntezę odpornego na działanie powietrza ligandu Sym-Phos o C,P-typie kompleksowania. Sym-Phos tworzy skuteczne palladowe katalizatory, mające wykorzystanie w trudnych przypadkach reakcji sprzęgania krzyżowego, prowadzonych w przyjaznych środowisku warunkach (woda, otwarta kolba, umiarkowana temperatura).

EN

We present cheap, quick and efficient three-phase synthesis of air-resistant Sym-Phos ligand {dicyclohexyl[3-(2,4,6-trimethoxyphenyl)-4-methoxynaphth-2-yl]phosphine} of C,P-type complexes. Sym-Phos creates effective palladium catalysts to be used in difficult cases of cross-coupling reactions carried out under favourable conditions for the environment (water, unplugged flask, moderate temperature).

3

Nanocząsteczkowe katalizatory palladowe w reakcjach tworzenia wiązań C-C

Trzeciak A. M., Ziółkowski J. J.

Wiadomości Chemiczne

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2009

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[Z] 63, 1-2

1-15

EN

The important role of palladium nanoparticles has been recently demonstrated in many catalytic systems designed for C-C bond forming reactions [1-4]. There are examples of catalytic systems described earlier as homogeneous in which Pd(0) nanoparticles were now identified. In the article three different palladium catalytic systems are discussed. In the first one, Pd(0) nanoparticles, obtained by chemical reduction of PdCl2 and stabilized by polyvinylpyrrolidone, were used for Heck coupling in [Bu4N]Br medium. Decrease of nanoparticles size in reaction conditions was explained as a result of dissolution of Pd(0) colloid and simultaneous formation of catalytically active monomolecular anionic palladium complexes [33]. The second example presents application of Pd(II) and Pd(0) supported on alumina-based oxides in Suzuki-Miyaura reaction [36]. Reduction of Pd(II) to Pd(0) nanoparticles under reaction conditions was confirmed. In contrast to the first described case, in Suzuki-Miyaura reaction the size of Pd(0) nanoparticles was the same before and after the catalytic cycle. The catalytic activity of both palladium forms was quite high, however Pd(0) formed in situ was slightly more efficient as catalyst. In the third part of the article studies of palladium reduction in anionic complexes of [IL]2[PdX4] type are shown, where IL = imidazolium cation [37]. These complexes catalyzed well Suzuki-Miyaura cross-coupling, but they were not stable under reaction conditions and decomposed to Pd(0) nanoparticles and Pd black. Using ESI-MS method it was possible to identify polynuclear (Pd3, Pd5) intermediate forms, stabilized with imidazolium cations or N-heterocyclic carbenes. In all systems discussed in the article co-existence of Pd(0) nanoparticles and monomolecular complexes was observed. That is important for understanding of the nature of catalytically active forms in C-C bond forming reactions.