Ligand-Dependent Diastereoselectivity in the Palladium-Catalyzed Copolymerization of Styrene with Carbon Monoxide

Gsponer, Achim; Schmid, Thomas; Consiglio, Giambattista

doi:10.1002/1522-2675(20011017)84:10<2986::aid-hlca2986>3.0.co;2-r

Cited by 29 publications

(10 citation statements)

References 20 publications

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“…In the field of ethylene homo-and co-, oligo-and polymerization Ni(II) complexes with a variety of P-N ligands were preferentially used [12][13][14][15][16][17]. Palladium complexes containing P-N ligands were applied as precatalysts for CO/alkene copolymerization; very high CO pressures (up to 320 bar) were required to have catalytic activity [17][18][19][20]. Some Pd(II) complexes with P-N ligands, such as phosphino-phosphinito-and phosphonitooxazolines, were applied in the CO/ethylene and CO/methyl acrylate copolymerization in the study of the stepwise insertion of the monomer on the precatalyst and resulting in the X-ray characterization of some intermediates [21][22][23].…”

Section: Introductionsupporting

confidence: 87%

“…These trends differed from the effect that benzoquinone typically shows in CO/alkene co-and terpolymerization reactions. For the latter reactions a linear relationship between [BQ]/[Pd] ratio and catalyst lifetime was observed together with no effect on the reaction rate [19,41]. The role played by benzoquinone in the copolymerization reactions is well understood and it consists in the oxidation of Pd(0) to Pd(II) with the concomitant formation of hydroquinone [42][43][44][45].…”

Section: Scheme 4 Styrene Dimerization Reactionmentioning

confidence: 99%

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New Chiral P-N Ligands for the Regio- and Stereoselective Pd-Catalyzed Dimerization of Styrene

et al. 2011

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Abstract:Two new chiral, enantiomerically pure, hybrid P-N ligands, namely (2R,5S)-2-phenyl-3-(2-pyridyl)-1,3-diaza-2-phosphanicyclo[3,3,0]octan-4-one (1) and (2R,5S)-2-phenyl-3-(2-pyridyl)-1,3-diaza-2-phosphanicyclo[3,3,0]octane (2), have been synthesized starting from L-proline. The two ligands differ in the presence or not of a carbonyl group in the diazaphosphane ring. Their coordination chemistry towards Pd(II) was studied by reacting them with [Pd(CH 3 )Cl(cod)]. A different behaviour was observed: ligand 2 shows the expected bidentate chelating behaviour leading to the mononuclear Pd-complex, while ligand 1 acts as a terdentate ligand giving a dinuclear species. The corresponding cationic derivatives were obtained from the palladium neutral complexes, both as mono-and dinuclear derivatives, and tested as precatalysts for styrene dimerization, yielding E-1,3-diphenyl-1-butene regio-and stereoselectively as the sole product. A detailed analysis of the catalytic behaviour is reported.

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Section: Introductionsupporting

confidence: 87%

Section: Scheme 4 Styrene Dimerization Reactionmentioning

confidence: 99%

New Chiral P-N Ligands for the Regio- and Stereoselective Pd-Catalyzed Dimerization of Styrene

et al. 2011

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“…This phenomenon is well known as back-skip in the catalytic synthesis of isotactic polypropene. 66 In the case of CO/alkene copolymerization the site selective coordination of the alkene was observed for both palladium complexes with amine-imine ligands, 27 with hybrid P-N ligands 48 and with the phosphino-phosphite (P-PO) molecule BINAPHOS. 67 A mechanistic hypothesis involving cis/trans isomerization was invoked.…”

Section: Reactivity Studiesmentioning

confidence: 60%

Catalyst activity or stability: the dilemma in Pd-catalyzed polyketone synthesis

et al. 2013

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A series of Pd-complexes containing nonsymmetrical bis(aryl-imino)acenaphthene (Ar-BIAN) ligands, featured by substituents on the meta positions of the aryl rings, have been synthesized, characterized and applied in CO/vinyl arene copolymerization reactions. Crystal structures of two neutral Pd-complexes have been solved allowing comparison of the bonding properties of the ligand. Kinetic and mechanistic investigations on these complexes have been performed. The kinetic investigations indicate that in general ligands with electron-withdrawing substituents give more active, but less stable, catalytic systems, although steric effects also play a role. The good performance observed with nonsymmetrical ligands is at least in part due to a compromise between catalyst activity and lifetime, leading to a higher overall productivity with respect to catalysts based on their symmetrical counterparts. Additionally, careful analysis of the reaction profiles provided information on the catalyst deactivation pathway. The latter begins with the reduction of a Pd(II) Ar-BIAN complex to the corresponding Pd(0) species, a reaction that can be reverted by the action

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“…The 13 C-NMR spectrum in the region of the ipso-C-atom shows a sharp band associated, at least, with the ll-triad [11]. The material is comparable with that obtained with the optically pure ligands (Figure, a), which shows high optical activity [12]. It is, however, remarkable that, when the copolymerization reaction is carried out with 3a in the presence of 1 mol-equiv.…”

mentioning

confidence: 99%

The Control of the Stereochemistry in the Palladium-Catalyzed Alternating Styrene/Carbon Monoxide Copolymerization: Effect of the Chirality of the Ligand and of the Ligand-to-Palladium Ratio, Preliminary Communication

Gsponer

Milani

Consiglio

2002

HCA

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Dedicated to Professor Dieter Seebach on the occasion of his 65th birthday Diaquapalladium(2 ) trifluoromethanesulfonates modified with (4R,4'S)-or (4S,4'S)-2,2'-bis(4-benzyl-4,5-dihydrooxazole) (C s -and C 2 -ligands) produce isotactic poly(1-oxo-2-phenylpropane-1,3-diyl) through copolymerization of styrene with carbon monoxide. However, the same meso-catalyst in the presence of the free ligand leads to prevailingly syndiotactic growth of the copolymer, whereas the optically active catalyst, when used in the presence of the free enantiomeric ligand, gives an atactic copolymer.Asymmetric catalysis leading to the synthesis of stereoregular copolymers has been a matter of intense interest [1] since the discovery of isotactic polypropylene and its rationalization based on the existence of enantiomorphic catalytic sites [2]. The discovery of the relationship between the symmetry properties of the catalytic system and the microstructure of the produced polymers in the case of the propene polymerization by zirconocene catalytic systems is particularly intriguing [3] [4].Despite the development of a variety of palladium-nitrogen-donor ligands catalytic systems to promote the synthesis of stereoregular styrene/carbon monoxide (CO) copolymers 1 [5], the factors involved in the enantioface discrimination during the related copolymerization of olefins with CO are much less understood [6] [7].We showed that [Pd(PP)(H 2 O) 2 ][OTf] 2 complexes (where PP is either (1R,1'S)-or (1RS,1'RS)-1,2-bis[1,1'-(diphenylphosphino)ethyl]benzene, OTf trifluoromethanesulfonate), when used as catalyst precursors for the copolymerization of propene with CO, produce both isotactic poly(1-methyl-2-oxopropane-1,3-diyl) [8]. The meso-ligand shows higher stereospecificity and much higher catalytic activity than the racemic-

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Ligand-Dependent Diastereoselectivity in the Palladium-Catalyzed Copolymerization of Styrene with Carbon Monoxide

Cited by 29 publications

References 20 publications

New Chiral P-N Ligands for the Regio- and Stereoselective Pd-Catalyzed Dimerization of Styrene

New Chiral P-N Ligands for the Regio- and Stereoselective Pd-Catalyzed Dimerization of Styrene

Catalyst activity or stability: the dilemma in Pd-catalyzed polyketone synthesis

The Control of the Stereochemistry in the Palladium-Catalyzed Alternating Styrene/Carbon Monoxide Copolymerization: Effect of the Chirality of the Ligand and of the Ligand-to-Palladium Ratio, Preliminary Communication

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