Comparing the Enantioselective Power of Steric and Electrostatic Effects in Transition‐Metal‐Catalyzed Asymmetric Synthesis

Poater, Albert; Ragone, Francesco; Mariz, Ronaldo; Dorta, Reto; Cavallo, Luigi

doi:10.1002/chem.201001938

Cited by 195 publications

(145 citation statements)

References 42 publications

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“…The method is currently used to calculate the buried volume of a given ligand [38], serving to quantify the proportion of the first coordination sphere of the metal occupied by this ligand [39]. Within this framework, one can distinguish encumbered zones (generally colour coded in brown) where the ligand protrudes like a mountain towards the reacting groups, thus limiting the space at their disposal [40], and empty zones (generally colour coded in blue) where the ligand retracts like a lake from the reacting groups [41,42].…”

Section: Resultsmentioning

confidence: 99%

How carbo-benzenes fit molecules in their inner core as do biologic ion carriers?

Turias

Poater²,

Chauvin

et al. 2015

Struct Chem

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The present computational study complements experimental efforts to describe and characterize carbo-benzene derivatives as paradigms of aromatic carbo-mers. A long-lasting issue has been the possibility of the π-electron crown of the C18 carbo-benzene ring to fit metals or any chemical agents in its core. A systematic screening of candidate inclusion complexes was carried out by density functional theory calculations. Mayer bond order, aromaticity indices, and energy decomposition analyses complete the understanding of the strength of the host-guest interaction. The change in steric and electronic properties induced by the guest agent is investigated by means of steric maps. Substitution of H atoms at the carbo-benzene periphery by electron-withdrawing or electron-donating groups is shown to have a determining influence on the stability of the inclusion complex ions: while electronegative substituents enhance the recognition of cations, electropositive substituents do the same for anions. The results confirm the experimental failure hitherto to evidence a carbo-benzene complex. Nevertheless, the affinity of carbo-benzene for the potassium cation appears promising for the design of planar hydrocarbon analogues of biologic ion carriersA.P. thanks the Spanish MINECO for a project CTQ2014-59832-JIN and European Commission for a Career Integration Grant (CIG09-GA-2011-293900

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Section: Resultsmentioning

confidence: 99%

How carbo-benzenes fit molecules in their inner core as do biologic ion carriers?

Turias

Poater²,

Chauvin

et al. 2015

Struct Chem

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“…Steric maps (29,30) based on calculated ground state geometries of 1-DMSO and 2b-DMSO show that all phosphine sulfonato ligands exert some steric pressure in the two bottom quadrants (Fig. 6 C and F) of the first coordination sphere around the palladium atom.…”

Section: Resultsmentioning

confidence: 99%

Breaking the regioselectivity rule for acrylate insertion in the Mizoroki–Heck reaction

Wucher

Caporaso

Roesle

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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In modern methods for the preparation of small molecules and polymers, the insertion of substrate carbon-carbon double bonds into metal-carbon bonds is a fundamental step of paramount importance. This issue is illustrated by Mizoroki-Heck coupling as the most prominent example in organic synthesis and also by catalytic insertion polymerization. For unsymmetric substrates H 2 C ¼ CHX the regioselectivity of insertion is decisive for the nature of the product formed. Electron-deficient olefins insert selectively in a 2,1-fashion for electronic reasons. A means for controlling this regioselectivity is lacking to date. In a combined experimental and theoretical study, we now report that, by destabilizing the transition state of 2,1-insertion via steric interactions, the regioselectivity of methyl acrylate insertion into palladiummethyl and phenyl bonds can be inverted entirely to yield the opposite "regioirregular" products in stoichiometric reactions. Insights from these experiments will aid the rational design of complexes which enable a catalytic and regioirregular MizorokiHeck reaction of electron-deficient olefins.density functional theory calculation | homogeneous catalysis | organometallic | regiochemistry W hereas the palladium-catalyzed Mizoroki-Heck coupling is an established powerful strategy for the formation of carbon-carbon bonds from electron-deficient and electron-rich olefins (1-5), insertion (co)polymerization (6-8) of acceptor or donor substituted olefins has only been demonstrated since the mid-1990s, and only a few catalyst motifs are known to promote such polymerizations (9, 10), which are based on palladium. The regioselectivity of insertion follows the same pattern for both reactions. Electron-deficient olefins [e.g., methyl acrylate (MA)] selectively insert in a 2,1-fashion (6, 9-11), whereas electron-rich olefins (e.g., vinyl ethers) insert in a 1,2-fashion (3, 6, 12-14, †) (Fig. 1). Finally, apolar olefins (e.g., α-olefins) commonly afford mixtures of both insertion modes in palladium-catalyzed Mizoroki-Heck (15) and polymerization reactions (16), whereas closely related nickel-catalyzed polymerizations of α-olefins can proceed with high selectivity by 1,2-insertion (17)-e.g., under kinetically controlled low-temperature conditions when sterically demanding ligands coordinate to nickel (16,18).The accepted rationale for these reactivity patterns is that electronic effects govern the regiochemistry of insertion for polarized carbon-carbon double bond substrates: In the Cossée-Arlman-type insertion step, the metal-bound, nucleophilic carbon atom migrates to the lower electron-density carbon atom of the double bond, while the electrophilic palladium atom migrates to the higher electron-density carbon atom of the double bond. In contrast, the insertion regiochemistry of apolar carbon-carbon double bonds is rather determined by steric effects (given that there is little electronic discrimination of the two olefinic carbon atoms), and under strict kinetic control the 1,2-insertion mode may preva...

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“…[15][16][17][18][19][20] Successful examples where the only chelating moieties are sulfoxides are still sporadic. [21][22][23][24][25][26][27][28] Complexes of bissulfoxide ligands with palladium and platinum are known, 22,[29][30][31][32][33][34] but there are not many reports of them being used successfully in catalysis. The only examples reported are from the groups of Shibasaki 22 and White, 33 using palladium bissulfoxides.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, Structure, and Catalytic Studies of Palladium and Platinum Bis-Sulfoxide Complexes

Drinkel

Linden

et al. 2013

Organometallics

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The bis-sulfoxide ligand p-tolyl-binaso and its derivatives can be used to synthesize neutral and cationic palladium and platinum complexes. Various Pt bis-sulfoxide complexes could be made by using the precursor Pt(M,SS,SS)-p-tolyl-binasoCl2 (5a) and abstracting the chlorides with silver salts. The Pd analogue of this compound (4) could not be used in the same way. In this case, the sulfoxides appear to be very weakly coordinated and different methods to make stable Pd bis-sulfoxide complexes had to be found. The nature of the bonding in the synthesized compounds was studied through analysis of their IR and NMR spectra and X-ray crystal structures. These studies revealed that the trans effect of other ligands in the complex is quite significant in determining the lability of the metal-sulfoxide bond. Some of the more stable platinum structures were then tested for their activity as catalysts in hydroboration and diboration reactions. AbstractThe bissulfoxide ligand, p-tolyl-binaso and its derivatives can be used to synthesize neutral and cationic palladium and platinum complexes. Various Pt bissulfoxide complexes could be made by using the precursor Pt{(M,S S ,S S )-p-tolyl-binaso}Cl 2 (5a) and abstracting the chlorides with silver salts. The Pd analogue of this compound (4) could not be used in the same way. In this case, the sulfoxides appear to be very weakly coordinated and different methods to make stable Pd bissulfoxide complexes had to be found. The nature of the bonding in the synthesized compounds was studied through analysis of their IR and NMR spectra and X-ray crystal structures. These studies revealed that the trans-effect of other ligands in the complex is quite significant in determining the lability of the metal-sulfoxide bond. Some of the more stable platinum structures were then tested for their activity as catalysts in hydroboration and diboration reactions.

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Comparing the Enantioselective Power of Steric and Electrostatic Effects in Transition‐Metal‐Catalyzed Asymmetric Synthesis

Cited by 195 publications

References 42 publications

How carbo-benzenes fit molecules in their inner core as do biologic ion carriers?

How carbo-benzenes fit molecules in their inner core as do biologic ion carriers?

Breaking the regioselectivity rule for acrylate insertion in the Mizoroki–Heck reaction

Synthesis, Structure, and Catalytic Studies of Palladium and Platinum Bis-Sulfoxide Complexes

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