Data-mining the diaryl(thio)urea conformational landscape: Understanding the contrasting behavior of ureas and thioureas with quantum chemistry

Luchini, Guilian; Ascough, David; Alegre‐Requena, Juan V.; Gouverneur, Véronique; Paton, Robert S.

doi:10.1016/j.tet.2018.12.033

Cited by 31 publications

(32 citation statements)

References 27 publications

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“…In the solid state, all novel phosphinourea Au(I) complexes display an intact Au–Cl bond with the P–Au–Cl axis nearly parallel to the biphenyl axis, as expected. The urea moiety generally adopts an anti , anti- conformation ( Au1, Au6 , Au10 , and Au13 ) but displays the much rarer anti,syn one 24 in Au4 and Au8 and shows various degrees of out-of-plane twisting of the aryl substituents (compare Au1 and Au10 in Scheme 3 ). In the solid state, the urea group establishes H-bonds either with chloride ligands or with other urea units, depending on the ligand scaffold.…”

Section: Resultsmentioning

confidence: 99%

H-Bonded Counterion-Directed Enantioselective Au(I) Catalysis

2022

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A new strategy for enantioselective transition-metal catalysis is presented, wherein a H-bond donor placed on the ligand of a cationic complex allows precise positioning of the chiral counteranion responsible for asymmetric induction. The successful implementation of this paradigm is demonstrated in 5- exo -dig and 6- endo- dig cyclizations of 1,6-enynes, combining an achiral phosphinourea Au(I) chloride complex with a BINOL-derived phosphoramidate Ag(I) salt and thus allowing the first general use of chiral anions in Au(I)-catalyzed reactions of challenging alkyne substrates. Experiments with modified complexes and anions, 1 H NMR titrations, kinetic data, and studies of solvent and nonlinear effects substantiate the key H-bonding interaction at the heart of the catalytic system. This conceptually novel approach, which lies at the intersection of metal catalysis, H-bond organocatalysis, and asymmetric counterion-directed catalysis, provides a blueprint for the development of supramolecularly assembled chiral ligands for metal complexes.

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Section: Resultsmentioning

confidence: 99%

H-Bonded Counterion-Directed Enantioselective Au(I) Catalysis

2022

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“…These computational methods were previously identified as amongst the most accurate for the evaluation of thiourea binding modes and conformations. [16,21] First, we investigated the conformationso ft hiourea 2g.O ur results, obtained with an implicit solvation model for toluene, indicate that the syn,anti conformation of 2g is preferred, as it is more stable than the commonly drawn anti,anti conformation by 2.0kcal mol À1 (Figure 1). Both these conformationse xhibit aO -H•••S hydrogen bond between the CF 3 CHOH and the thiocarbonyl functional groups.T he most stable anti,syn and syn,syn conformations of thiourea 2g werea tl east 4.0 kcal mol À1 higher in energy.O ur results are in line with literature precedents that have established that the anti,anti and syn,anti conformations are both accessible for diphenylthioureas in solution.…”

Section: Resultsmentioning

confidence: 99%

“…Both these conformationse xhibit aO -H•••S hydrogen bond between the CF 3 CHOH and the thiocarbonyl functional groups.T he most stable anti,syn and syn,syn conformations of thiourea 2g werea tl east 4.0 kcal mol À1 higher in energy.O ur results are in line with literature precedents that have established that the anti,anti and syn,anti conformations are both accessible for diphenylthioureas in solution. [16,21] In addition, Xray structures of 2c and 2h revealed that both thiourea and alcohol groups were involved in hydrogen bonding. [22] In particular,f or 2h as hort intramolecular H-bond (2.25 )w as observedb etween the OH andC =Sgroups.…”

Section: Resultsmentioning

confidence: 99%

Thiourea‐Catalyzed C−F Bond Activation: Amination of Benzylic Fluorides

Houle

Savoie

Davies

et al. 2020

Chemistry A European J

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We describe the first thiourea‐catalyzed C−F bond activation. The use of a thiourea catalyst and Ti(OiPr)4 as a fluoride scavenger allows the amination of benzylic fluorides to proceed in moderate to excellent yields. Preliminary results with S‐ and O‐based nucleophiles are also presented. DFT calculations reveal the importance of hydrogen bonds between the catalyst and the fluorine atom of the substrate to lower the activation energy during the transition state.

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“…6,31,32 This hydrogen bonding ability is governed by a combination of factors including the Brønsted acidity 17,33 and the conformational preferences of the dual hydrogen bond donor motifs. 2,16,17,34 Both of these factors are important when designing anion receptors and organocatalysts; energetic penalties apply if a conformational change is required for the formation of both H-bonds to a guest or substrate, while it is generally accepted that increased Brønsted acidity correlates with an increase in hydrogen bond strength 2 that is required for effective substrate binding.…”

Section: ■ Introductionmentioning

confidence: 99%

Diaminomethylenemalononitriles and Diaminomethyleneindanediones as Dual Hydrogen Bond Donors for Anion Recognition

et al. 2021

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Diaminomethylenemalononitriles (DMMs) and diaminomethyleneindanediones (DMIs) are dual H-bond donors that have previously been used as organocatalysts, but their anion binding ability has not been investigated. We report the synthesis of both alkyl- and aryl-substituted DMMs and DMIs, together with a comparison of their anion binding ability with that of the analogous thioureas. The DMMs display affinity for monovalent anions, with similar anion binding affinities observed to that of the thioureas in acetonitrile, albeit with differing trends for the N,N′-dialkyl versus N,N′-diaryl compounds. In contrast, the DMIs do not bind to monovalent anions under similar conditions as a result of conformational locking through the formation of intramolecular H-bonds. This can be overcome upon addition of sulfate ions, and binding of sulfate is enhanced in a more competitive solvent (DMSO).

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Data-mining the diaryl(thio)urea conformational landscape: Understanding the contrasting behavior of ureas and thioureas with quantum chemistry

Cited by 31 publications

References 27 publications

H-Bonded Counterion-Directed Enantioselective Au(I) Catalysis

H-Bonded Counterion-Directed Enantioselective Au(I) Catalysis

Thiourea‐Catalyzed C−F Bond Activation: Amination of Benzylic Fluorides

Diaminomethylenemalononitriles and Diaminomethyleneindanediones as Dual Hydrogen Bond Donors for Anion Recognition

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