Synthesis and characterization of κ-2-bis-N-heterocyclic carbene rhodium(I) catalysts: Application in enantioselective arylboronic acid addition to cyclohex-2-enones

Jeletic, Matthew S.; Lowry, Roxy J.; Swails, Jason M.; Ghiviriga, Ion; Veige, Adam S.

doi:10.1016/j.jorganchem.2011.05.015

Cited by 13 publications

(10 citation statements)

References 92 publications

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“…Chiral di- N -heterocyclic carbene (diNHC) ligands bind a metal via two M–carbene bonds with the carbene heterocycles tethered typically by a chiral fragment. A recent surge in application of chiral diNHC–metal complexes in asymmetric catalysis − prompted studies to develop a method to quantify the relative flexibility within the linking unit of diNHC ligands.…”

Section: Introductionmentioning

confidence: 99%

Chemical Exchange Saturation Transfer (CEST) as a Tool to Measure Ligand Flexibility of Chelating Chiral Di-N-heterocyclic Carbene Complexes

et al. 2011

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A series of eight [(diNHC)Rh(CO)2][OTf] complexes, 1′-R, 2′-R, and 3′-R (where diNHC = DEAM, trans-9,10- d ihydro-9,10- e thano a nthracene-11,12-diyl m ethanediyl carbene, and DEA, trans-9,10- d ihydro-9,10- e thano a nthracene-11,12-diyl carbene ligands; R = R-methylphenylmethane (R-CHMePh), diphenylmethane (diPh), benzyl (Bn), methyl (Me), isopropyl ( i Pr), and o-methylbenzyl (o-MeBn); carbene heterocycle = imidazol-2-ylidene, and benzimidazol-2-ylidene), are synthesized and characterized. The purpose for the synthesis of these complexes was to examine the relationship between carbene N-heterocycle, R-group substitution, and metallocycle ring size (DEAM = 9, DEA = 7 atom ring) on ligand flexibility. The complexes were examined by chemical exchange saturation transfer to measure the rate of conformational isomerization. The results indicate that flexibility is not significantly altered by choice of carbene heterocycle and R group. However, the constrained DEA diNHC derivative does not undergo conformational isomerization.

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Section: Introductionmentioning

confidence: 99%

Chemical Exchange Saturation Transfer (CEST) as a Tool to Measure Ligand Flexibility of Chelating Chiral Di-N-heterocyclic Carbene Complexes

et al. 2011

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“…DMBI‐BDZC has been used to generate chiral rhodium (I) bis(N‐heterocyclic carbene) complexes by C=C bond cleavage . Such complexes are useful enantioselective catalysts . However, our interest in DMBI‐BDZC lies in its electron‐rich enetetramine core, since such electron rich alkenes are known to serve as n‐type dopants .…”

Section: Introductionmentioning

confidence: 99%

Introducing a Nonvolatile N‐Type Dopant Drastically Improves Electron Transport in Polymer and Small‐Molecule Organic Transistors

Panidi

Kainth

Paterson

et al. 2019

Adv Funct Materials

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Molecular doping is a powerful yet challenging technique for enhancing charge transport in organic semiconductors (OSCs). While there is a wealth of research on p-type dopants, work on their n-type counterparts is comparatively limited. Here, reported is the previously unexplored n-dopant (12a,18a)-5,6,12,12a,13,18,18a,19-octahydro-5,6-dimethyl-13,18[1′,2′]-ben- zenobisbenzimidazo [1,2-b:2′,1′-d]benzo[i][2.5]benzodiazo-cine potassium triflate adduct (DMBI-BDZC) and its application in organic thin-film transistors (OTFTs). Two different high electron mobility OSCs, namely, the polymer poly[[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6diyl]-alt-5,5′-(2′-bithiophene)] and a small-molecule naphthalene diimides fused with 2-(1,3-dithiol-2-ylidene)malononitrile groups (NDI-DTYM2) are used to study the effectiveness of DMBI-BDZC as a n-dopant. N-doping of both semiconductors results inOTFTs with improved electron mobility (up to 1.1 cm 2 V −1 s −1 ), reduced threshold voltage and lower contact resistance. The impact of DMBI-BDZC incorporation is particularly evident in the temperature dependence of the electron transport, where a significant reduction in the activation energy due to trap deactivation is observed. Electron paramagnetic resonance measurements support the n-doping activity of DMBI-BDZC in both semiconductors. This finding is corroborated by density functional theory calculations, which highlights ground-state electron transfer as the main doping mechanism. The work highlights DMBI-BDZC as a promising n-type molecular dopant for OSCs and its application in OTFTs, solar cells, photodetectors, and thermoelectrics.

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“…Iglesias and Sánchez et al reported the asymmetric hydrogenation of alkenes with bis(NHC) derived from tartaric acid [50,51]. A chiral palladium allyl complex bearing bis(NHC)/cyclophane ligand for 1,4-addition of phenylboronic acid to 2-cyclohexen-1-one was synthesized by Veige et al [52,53].…”

Section: Introductionmentioning

confidence: 99%

(±)-trans-1,2-Cyclohexanediamine-Based Bis(NHC) Ligand for Cu-Catalyzed Asymmetric Conjugate Addition Reaction

et al. 2019

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Bis(NHC) ligand precursors, L1, based on trans-1,2-diaminocyclohexane were designed and synthesized. To introduce chirality at the hydroxyamide side arm on the NHC of L1, a chiral β-amino alcohol, such as enantiopure leucinol, was used. Cu-catalyzed asymmetric conjugate addition reactions of cyclic and acyclic enones with Et2Zn were selected to evaluate the performance of L1 as a chiral ligand. For the reaction of cyclic enone, a combination of [bis(trimethylsilyl)acetylene]-(hexafluoroacetylacetonato)copper(I) (Cu(hfacac)(btmsa)) with a (±)-trans-1,2-cyclohexanediamine-based bis(NHC) ligand precursor, (rac; S,S)-L1, which was prepared from (S)-leucinol, was the most effective. Thus, treating 2-cyclohexen-1-one (3) with Et2Zn in the presence of catalytic amounts of Cu(hfacac)(btmsa) and (rac; S,S)-L1 afforded (R)-3-ethylcyclohexanone ((R)-4) with 97% ee. Similarly, use of (rac; R,R)-L1, which was prepared from (R)-leucinol, produced (S)-4 with 97% ee. Conversely, for the asymmetric 1,4-addition reaction of the acyclic enone, optically pure (−)-trans-1,2-cyclohexanediamine-based bis(NHC) ligand precursor, (R,R; S,S)-L1, worked efficiently. For example, 3-nonen-2-one (5) was reacted with Et2Zn using the CuOAc/(R,R; S,S)-L1 catalytic system to afford (R)-4-ethylnonan-2-one ((R)-6) with 90% ee. Furthermore, initially changing the counterion of the Cu precatalyst between an OAc and a ClO4 ligand on the metal reversed the facial selectivity of the approach of the substrates. Thus, the conjugate addition reaction of 5 with Et2Zn using the Cu(ClO4)2/(R,R; S,S)-L1 catalytic system, afforded (S)-6 with 75% ee.

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Synthesis and characterization of κ-2-bis-N-heterocyclic carbene rhodium(I) catalysts: Application in enantioselective arylboronic acid addition to cyclohex-2-enones

Cited by 13 publications

References 92 publications

Chemical Exchange Saturation Transfer (CEST) as a Tool to Measure Ligand Flexibility of Chelating Chiral Di-N-heterocyclic Carbene Complexes

Chemical Exchange Saturation Transfer (CEST) as a Tool to Measure Ligand Flexibility of Chelating Chiral Di-N-heterocyclic Carbene Complexes

Introducing a Nonvolatile N‐Type Dopant Drastically Improves Electron Transport in Polymer and Small‐Molecule Organic Transistors

(±)-trans-1,2-Cyclohexanediamine-Based Bis(NHC) Ligand for Cu-Catalyzed Asymmetric Conjugate Addition Reaction

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