Step by step palladium mediated syntheses of new 2-(pyridin-2-yl)-6-R-nicotinic acids and esters

Petretto, Giacomo Luigi; Zucca, Antonio; Stoccoro, Sergio; Cinellu, Maria Agostina; Minghetti, Giovanni

doi:10.1016/j.jorganchem.2009.10.002

Cited by 27 publications

(17 citation statements)

References 14 publications

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“…112 In contrast, with palladium acetate, no evidence for C(3)-metalation of unsubstituted 2,2 0 -bipyridine was found. 113 An interesting dinuclear complex 17 (Fig. 7) could be produced after only 3 h, in 97% yield, in the reaction of [Pt (CH 3 ) 2 (DMSO) 2 ] with terpy (terpy ¼ 2,2 0 :6 0 ,2 00 -terpyridine) when employed in a 2 : 1 ratio.…”

Section: A Renaissancementioning

confidence: 99%

“…Surprisingly, in several instances, quite weakly polar solvents, like benzene, toluene, or dichloromethane, have been used for the generation of ''rollover'' cyclometalated bipy complexes. 101,107,108,[110][111][112][113][114]185 Nevertheless, at least traces of a stabilizing agent seem to be mandatory for the reactions to proceed. Although [Pt(bipy À H)(CH 3 )(DMSO)] (16) (34) undergoes ''rollover'' cyclometalation upon heating in the presence of donor ligands such as dimethyl sulfide (see Fig.…”

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confidence: 99%

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“Rollover” cyclometalation – early history, recent developments, mechanistic insights and application aspects

2012

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''Rollover'' cyclometalation constitutes a special case among the well-known class of cyclometalation reactions. An overview is given that covers the very first description of this reaction type, as well as recent developments. In addition, not only condensed-phase experiments are reviewed, but also investigations based on mass spectrometric techniques, together with ''in silico'' studies using DFTbased calculations are considered. While the latter two methods allow for a detailed analysis of the intrinsic factors that affect the reaction mechanisms, consideration of all three regimes permits to develop a coherent mechanistic picture and to address the often noted gap between condensed-and gasphase studies. Moreover, the quite unexpected reactivity of ''rollover'' cyclometalated complexes in gasphase experiments, as well as potential applications, e.g. in synthetic procedures, are discussed in some detail.

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Section: A Renaissancementioning

confidence: 99%

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confidence: 99%

“Rollover” cyclometalation – early history, recent developments, mechanistic insights and application aspects

2012

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“…Taking advantage of rollover cyclometalation, in 2010, Zucca and coworkers reported a first application of rollover functionalization of 2,2′-bipyridines. The authors showed that dinuclear palladium(II) rollover derivatives [Pd(N^C)Cl] 2 111 react in ethanol with CO, under pressure at 60 °C, affording the corresponding esters and acids, 112 and 113 , respectively ( Figure 57 ) [ 111 ]. As key steps of the process were proposed insertion of CO into the palladium–carbon bond (leading an unstable six-membered acyl complex, subsequent nucleophilic attack of ethanol on the acylic carbonyl, and final extrusion of the organic product with reductive elimination of palladium.…”

Section: Organic Synthesis (Stochiometric Functionalization)mentioning

confidence: 99%

Rollover Cyclometalation as a Valuable Tool for Regioselective C–H Bond Activation and Functionalization

Zucca

Pilo

2021

Molecules

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Rollover cyclometalation constitutes a particular case of cyclometallation reaction. This reaction occurs when a chelated heterocyclic ligand loses its bidentate coordination mode and undergoes an internal rotation, after which a remote C–H bond is regioselectively activated, affording an uncommon cyclometalated complex, called “rollover cyclometalated complex”. The key of the process is the internal rotation of the ligand, which occurs before the C–H bond activation and releases from coordination a donor atom. The new “rollover” ligand has peculiar properties, being a ligand with multiple personalities, no more a spectator in the reactivity of the complex. The main reason of this peculiarity is the presence of an uncoordinated donor atom (the one initially involved in the chelation), able to promote a series of reactions not available for classic cyclometalated complexes. The rollover reaction is highly regioselective, because the activated C–H bond is usually in a symmetric position with respect to the donor atom which detaches from the metal stating the rollover process. Due to this novel behavior, a series of potential applications have appeared in the literature, in fields such as catalysis, organic synthesis, and advanced materials.

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“…Due to their intriguing peculiarities, rollover complexes are attracting a growing interest in recent years, as demonstrated by the rising number of papers, among which some have recent reviews [4,26,27]. The interest is focused on the reactivity of these species [28][29][30][31] and to applications in organic synthesis [32][33][34][35] and catalysis [9][10][11][12][13][14][15][16][17][18][19], as well as chemosensors [36], luminescent devices [37], and potent antitumor agents [38][39][40][41][42][43].…”

Section: Introductionmentioning

confidence: 99%

Pt(II) Derivatives with Rollover-Coordinated 6-substituted 2,2′-bipyridines: Ligands with Multiple Personalities

et al. 2020

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We report here the synthesis, characterization and behavior of a series of Pt(II) cyclometalated rollover complexes with two substituted bipyridines, 6-ethyl-2,2′-bipyridine (bpy6Et) and 6-methoxy-2,2′-bipyridine (bpy6OMe), in comparison with previously studied 2,2′-bipyridine complexes. The two ligands have similar steric hindrance but different electronic properties. As a result, the reactivity of the two series of complexes follows very different routes. In particular, the new complexes behave differently towards protonation reactions, differences given by substituents and ancillary ligands, added to the presence of several nucleophilic centers. Reaction of complex [Pt(bpy6OMe-H)(PPh3)Me)] with [H3O⋅18-crown-6][BF4] results in a retro-rollover reaction whose final product is the cationic adduct [Pt(bpy6OMe)(PPh3)Me)]+. Surprisingly, only the isomer with the cis-PPh3-OMe geometry is formed; in spite of an expected instability due to steric hindrance, Density-Functional theory (DFT) calculations showed that this isomer is the most stable. This result shows that the cone angle is far from being a real “solid cone” and should lead to a different interpretation of well-known concepts concerning steric bulk of ligands, such as cone angle. Proton affinity values of ligands, neutral complexes and their protonated counterparts were analyzed by means of DFT calculations, allowing a comparison of their properties.

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Step by step palladium mediated syntheses of new 2-(pyridin-2-yl)-6-R-nicotinic acids and esters

Cited by 27 publications

References 14 publications

“Rollover” cyclometalation – early history, recent developments, mechanistic insights and application aspects

“Rollover” cyclometalation – early history, recent developments, mechanistic insights and application aspects

Rollover Cyclometalation as a Valuable Tool for Regioselective C–H Bond Activation and Functionalization

Pt(II) Derivatives with Rollover-Coordinated 6-substituted 2,2′-bipyridines: Ligands with Multiple Personalities

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