Chemoselective homogeneous hydrogenation of phenylacetylene using thiosemicarbazone and thiobenzoylhydrazone palladium(II) complexes as catalysts

Pelagatti, Paolo; Venturini, A; Leporati, Andrea; Carcelli, Mauro; Costa, Mirco; Bacchi, Alessia; Pelizzi, Giancarlo; Pelizzi, Corrado

doi:10.1039/a804052d

Cited by 76 publications

(50 citation statements)

References 35 publications

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“…[7,8] The only homogeneous palladium(0) catalyst is the complex [Pd 2 (dppm) 3 ], which shows low activity in the hydrogenation of propyne and 2-butyne.…”

mentioning

confidence: 99%

Selective Homogeneous Palladium(0)-Catalyzed Hydrogenation of Alkynes to (Z)-Alkenes

Laren

Elsevier

1999

Angew. Chem. Int. Ed.

242

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The selective semihydrogenation of alkynes to (Z)-alkenes seems to be a simple reaction, yet this type of conversion remains a desirable synthetic tool. A variety of catalysts is available for the conversion of alkynes into (Z)-alkenes; the best known and most efficient ones are heterogeneous catalysts such as the Lindlar catalyst, [1] nickel boride, [2] the ªP2Niº catalyst, [3] and palladium immobilized on a clay.[4]Especially the Lindlar catalyst suffers from a number of major problems in the selective cis-hydrogenation of alkynes, notably, partial isomerization of the (Z)-alkene product to the (E)-alkene, shift of the double bond, overreduction to the alkane, and problems with reproducibility. Only a few examples are known of homogeneous catalyst systems that show good selectivity for a wider range of substrates, for example, rhodium- [5] and Cr(CO) 3 -catalyzed hydrogenation.[6]For palladium, however, few homogeneous catalyst systems are known, and these involve palladium(ii) complexes. [7,8] The only homogeneous palladium(0) catalyst is the complex [Pd 2 (dppm) 3 ], which shows low activity in the hydrogenation of propyne and 2-butyne.[9]Here we report the first example of a homogeneous palladium(0) catalyst bearing a bidentate nitrogen ligand that is able to homogeneously hydrogenate a wide variety of alkynes to the corresponding (Z)-alkenes with very high selectivity. Additionally, enynes are selectively converted into dienes. As part of our continuing interest in carbon ± element (e.g., CÀC, CÀH, CÀN, CÀX) bond-forming reactions, [10] we employed zerovalent palladium precatalysts I, which contain the rigid bidentate nitrogen ligand bis(arylimino)acenaphthene (bian). These have previously been isolated with an electrondeficient alkene as the ancillary ligand; [11] however, analogues of I with electron-rich alkenes are not stable. We reasoned that since simple alkenes are expected to be readily substituted by alkynes, if alkynes were hydrogenated in the presence of molecular hydrogen, subsequent fast substitution by excess alkyne could give rise to a viable catalytic cycle (Scheme 1). Scheme 1. Proposed catalytic cycle for hydrogenation of alkynes.We conducted hydrogenation reactions of alkynes at 20 8C and 1 bar hydrogen pressure with initial sample concentrations of about 0.5 m in THF and 1 mol % of I a as precatalyst. With 3-hexyne (1) and 4-octyne (3), high stereoselectivity (b 99.5 %) for the formation of (Z)-3-hexene and (Z)-4-octyne was observed, and hydrogenation proceeded with excellent yield. Various other alkynes were then subjected to these hydrogenation conditions (Table 1).The stereoselectivity for the formation of the (Z)-alkene is generally excellent and in many cases superior to that obtained with Lindlar [1] or P2Ni catalysts [3] and comparable to or in several cases better than those of known homogeneous systems.[5±7] Generally, quantitative conversion of the alkyne to the desired (Z)-alkene takes place, without concomitant alkane formation. The selectivity is highest (Z/E b 99/1) for s...

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“…[7,8] The only homogeneous palladium(0) catalyst is the complex [Pd 2 (dppm) 3 ], which shows low activity in the hydrogenation of propyne and 2-butyne.…”

mentioning

confidence: 99%

Selective Homogeneous Palladium(0)-Catalyzed Hydrogenation of Alkynes to (Z)-Alkenes

Laren

Elsevier

1999

Angew. Chem. Int. Ed.

242

View full text Add to dashboard Cite

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“…However, the surface of these catalysts is a rather complex assembly of various domains, each of which contributes to the product distribution in its own way, often resulting in unpredictable overall results. In order to circumvent the presence of different palladium species, much attention has been devoted to the application of homogeneous mononuclear palladium complexes; either in the form of a Pd(II) complex [32,33] or a Pd(0) compound [34][35][36]. In most of the reported cases, these mononuclear palladium complexes display a higher chemo-and (sometimes) higher stereoselectivity than the heterogeneous counterparts.…”

Section: Palladium Catalystsmentioning

confidence: 99%

“…Members of the Parma group have shown that a large variety of divalent palladium complexes, with the generic formula [Pd(L)X] (X = OAc -or Cl -) bearing a hydrazinato-based tridentate ligand L (containing different donor atoms), are able to hydrogenate alkynes to the corresponding alkenes with different degrees of success [32,[50][51][52]. Considerable mechanistic details have been reported for this reaction employing the catalysts [Pd(thiosemicarbazonato)X] (28) and [Pd(thiobenzoylhydrazonato)X] (29) (see Fig.…”

Section: Palladium Catalystsmentioning

confidence: 99%

Homogeneous Hydrogenation of Alkynes and Dienes

Elsevier¹,

Kluwer²

2006

The Handbook of Homogeneous Hydrogenation

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“…[3] Costa, Pelagatti et al have recently studied the hydrogenation activity of palladium() complexes stabilized by polydentate PʝNʝO, [4,5] NʝNʝS, [6] and NʝNʝN ligands. [7] In particular, the use of tridentate nitrogen donor ligands gave rise to relatively efficient Pd II hydrogenation catalysts.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Structures and Catalytic Properties of Bis(2‐pyridylimino)‐ isoindolatopalladium Complexes

et al. 2004

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Reaction of the bis(2‐pyridylimino)isoindole derivatives (10‐Me)‐BPI (1a), (11‐Me)‐BPI (1b), (11‐Br)‐BPI (1c), (4‐Me)‐BPI (1d) and 4‐Me‐10‐tBuBPI (1e) with [PdCl2(PhCN)2] and triethylamine in benzene gave the square‐planar palladium(II) complexes [PdCl{(10‐Me)‐BPI}] (2a), [PdCl{(11‐Me)‐BPI}] (2b), [PdCl{(11‐Br)‐BPI}] (2c), [PdCl(4‐MeBPI)] (2d) and [PdCl(4‐Me‐10‐tBuBPI)] (2e), respectively. Extraction of the crude product 2b with aqueous sodium carbonate solution led to the formation of the dinuclear carbonato‐bridged complex [{(11‐Me‐BPI)Pd}2(μ‐CO3)] (3) which was characterized by an X‐ray structure analysis. Reaction of 11‐Br‐BPI (1c) with a large excess (6 equiv.) of the acetylenes Me3SiCCH, Ph3SiCCH and PhCCH under Sonogashira conditions gave the alkynylated derivatives 11‐(Me3SiCC)‐BPI (4a), 11‐(Ph3SiCC)‐BPI (4b) and 11‐(PhCC)‐BPI (4c), which were metallated with bis(benzonitrile)dichloropalladium(II) to yield the PdII complexes [PdCl{11‐(Me3SiCC)‐BPI}] (5a), [PdCl{11‐(Ph3SiCC)‐BPI}] (5b) and [PdCl{11‐(PhCC)‐BPI}] (5c), respectively. The activity of 2b in the catalytic hydrogenation of C=C double bonds was tested for the reaction with styrene, 1‐octene and cyclohexene. The stability of the palladium complex, the reproducibility of the reaction kinetics, the different behaviour towards the three olefins chosen as substrates, as well as the possibility of isolating the non‐decomposed catalyst after several catalytic runs, provides circumstantial evidence for molecular catalysis with the BPI‐palladium complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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Chemoselective homogeneous hydrogenation of phenylacetylene using thiosemicarbazone and thiobenzoylhydrazone palladium(II) complexes as catalysts

Cited by 76 publications

References 35 publications

Selective Homogeneous Palladium(0)-Catalyzed Hydrogenation of Alkynes to (Z)-Alkenes

Selective Homogeneous Palladium(0)-Catalyzed Hydrogenation of Alkynes to (Z)-Alkenes

Homogeneous Hydrogenation of Alkynes and Dienes

Synthesis, Structures and Catalytic Properties of Bis(2‐pyridylimino)‐ isoindolatopalladium Complexes

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