Multicomponent Synthesis of Chiral Bidentate Unsymmetrical Unsaturated <i>N</i>‐Heterocyclic Carbenes: Copper‐Catalyzed Asymmetric CC Bond Formation

Jahier-Diallo, Claire; Morin, Marie S. T.; Queval, Pierre; Rouen, Mathieu; Artur, Isabelle; Querard, Pierre; Toupet, Loı̈c; Crévisy, Christophe; Baslé, Olivier; Mauduit, Marc

doi:10.1002/chem.201405765

Cited by 59 publications

(38 citation statements)

References 44 publications

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“…Indeed, the ring‐opening reactions of epoxides with arylimidazoles do not appear facile because, to the best of our knowledge, no such precedent has been reported in the literature. By using the so‐called Arduengo synthetic procedure that was recently optimised to yield unsymmetrical imidazoliums, we prepared the targeted salt by the one‐pot reaction of 2,4,6‐trimethylaniline and 1‐amino‐2‐methyl‐2‐propanol. This afforded the desired unsymmetrical imidazolium salt, namely 1‐mesityl‐3‐(2‐hydroxyisobutyl)imidazolium hexafluorophosphate ([H 2 L][PF 6 ], 1 ), in a fair isolated yield of 51 % (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Early/Late Heterobimetallic Tantalum/Rhodium Species Assembled Through a Novel Bifunctional NHC‐OH Ligand

Srivastava

Moneuse

Petit

et al. 2018

Chemistry A European J

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The straightforward synthesis of a new unsymmetrical hydroxy-tethered N-heterocyclic carbene (NHC) ligand, HL, is presented. The free ligand exhibits an unusual OH-carbene hydrogen-bonding interaction. This OH-carbene motif was used to yield 1) the first tantalum complex displaying both a Fischer- and Schrock-type carbene ligand and 2) a unique NHC-based early/late heterobimetallic complex. More specifically, the protonolysis chemistry between the ligand's hydroxy group and imido-alkyl or alkylidene-alkyl tantalum precursor complexes yielded the rare monometallic tantalum-NHC complexes [Ta(XtBu)(L)(CH tBu) ] (X=N, CH), in which the alkoxy-carbene ligand acts as a chelate. In contrast, HL only binds to rhodium through the NHC unit in [Rh(HL)(cod)Cl] (cod=cycloocta-1,5-diene), the hydroxy pendant arm remaining unbound. This bifunctional ligand scaffold successfully promoted the assembly of rhodium/tantalum heterobimetallic complexes upon either 1) the insertion of [Rh(cod)Cl] into the Ta-NHC bond in [Ta(NtBu)(L)(CH tBu) ] or 2) protonolysis between the free hydroxy group in [Rh(HL)(cod)Cl] and one alkyl group in [Ta(NtBu)(CH tBu) ].

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Section: Resultsmentioning

confidence: 99%

Early/Late Heterobimetallic Tantalum/Rhodium Species Assembled Through a Novel Bifunctional NHC‐OH Ligand

Srivastava

Moneuse

Petit

et al. 2018

Chemistry A European J

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“…Besides chiral amines, amino alcohols 29 were also utilized in the synthesis of C 2 -symmetric gold(I) complexes 34. The respective NHC precursors 33 were obtained via a one-pot protocol [39,75] and were subsequently transformed into gold complexes by the reaction with AuCl•SMe 2 in acetone, mediated by K 2 CO 3 . However, the yield was strictly dependent on the substituents.…”

Section: Cyclic C 2 -Symmetric Gold(i) Complexesmentioning

confidence: 99%

“…Catalysts 2019, 9, A straightforward approach to imidazolium salts 112 and gold(I) complexes 113 has recently been developed by Toste (Scheme 17) [74]. Implementing Baslé and Mauduit's protocol [39,75], the authors have prepared a series of C1-symmetric NHC precursors via an elegant one-pot protocol, directly from chiral β-amino alcohols 29, mesityl amine (110), glyoxal (30), and paraformaldehyde (31). The developed protocol includes two experimentally common steps.…”

Section: Scheme 10mentioning

confidence: 99%

“…Although some advances have been achieved using phosphine ligands, their tedious synthesis and, in some cases, intrinsic ease of oxidation excludes practical applications on a large scale. In contrast, the rigid structure of NHCs (N-heterocyclic carbenes) provides an excellent opportunity to form stable gold complexes with a well-defined chiral environment, as was proven in the case of other metals, such as palladium [26][27][28][29], ruthenium [30][31][32][33] or copper [34][35][36][37][38][39][40][41][42]. Moreover, adequately planned structure of NHC ligands allows for tuning of their electronic and steric properties, which is not easily achievable in the case of phosphines [43,44].…”

Section: Introductionmentioning

confidence: 99%

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Chiral N-heterocyclic Carbene Gold Complexes: Synthesis and Applications in Catalysis

Michalak

Kośnik

2019

Catalysts

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N-Heterocyclic carbenes have found many applications in modern metal catalysis, due to the formation of stable metal complexes, and organocatalysis. Among a myriad of N-heterocyclic carbene metal complexes, gold complexes have gained a lot of attention due to their unique propensity for the activation of carbon-carbon multiple bonds, allowing many useful transformations of alkynes, allenes, and alkenes, inaccessible by other metal complexes. The present review summarizes synthetic efforts towards the preparation of chiral N-heterocyclic gold(I) complexes exhibiting C 2 and C 1 symmetry, as well as their applications in enantioselective catalysis. Finally, the emerging area of rare gold(III) complexes and their preliminary usage in asymmetric catalysis is also presented. Scheme 3. The synthesis of a gold(I) complex from (R)-1-aminotetralin.An elegant approach to C2-symmetric gold(I) complexes was described by Czekelius et al. [72] (Scheme 4), inspired by previous Herrmann's work [73]. The synthetic approach involves chiral amines 24, readily available from the corresponding phenylacetic acid 22 via the Friedel-Crafts reaction of bromobenzene and fractional crystallization of the corresponding tartaric acid amine salt upon reductive amination. The resulting amine 24 was further formylated and subjected to Bischler-Napieralski cyclization to give 3-aryl-substituted dihydroisoquinoline 25. Subsequent reductive coupling afforded the basic diamine skeleton 26 into a single diastereomer, which appeared a perfect platform for structural ligand diversification via Suzuki coupling. The functionalized diamines 26 were then cyclized into imidazolium salts 27 with triethyl orthoformate to give the products with yields in the range of 49-94% (for selected examples, see Scheme 4). The formation of gold(I) complexes 28 was accomplished under rather unusual conditions, by the reaction of gold(I) chloride with a carbene generated by the action of KOtBu. Scheme 4. The synthesis of C2-symmetric gold(I) complexes accessible via a reductive coupling. The application of other chiral building blocks has recently been reported by the Toste group (Scheme 5) [74]. Besides chiral amines, amino alcohols 29 were also utilized in the synthesis of C2-Scheme 3. The synthesis of a gold(I) complex from (R)-1-aminotetralin.An elegant approach to C 2 -symmetric gold(I) complexes was described by Czekelius et al. [72] (Scheme 4), inspired by previous Herrmann's work [73]. The synthetic approach involves chiral amines 24, readily available from the corresponding phenylacetic acid 22 via the Friedel-Crafts reaction of bromobenzene and fractional crystallization of the corresponding tartaric acid amine salt upon reductive amination. The resulting amine 24 was further formylated and subjected to Bischler-Napieralski cyclization to give 3-aryl-substituted dihydroisoquinoline 25. Subsequent reductive coupling afforded the basic diamine skeleton 26 into a single diastereomer, which appeared a perfect platform for structural ligand diversification via Suzuki...

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“…Hence, the tethered alkoxide serves as an intramolecular catalytic proton source after heterolytic H 2 cleavage, effecting the transfer of both Ha toms from H 2 to the alkyne.A lkoxide-tethered Cu complexes 5 should be accessible from previously reported alcohol-substituted N-heterocyclic carbene (NHC) ligand precursors 4 ( Figure 1). [36][37][38] The envisaged transformationwas optimized using the semihydrogenation of alkyne 7 as at est reaction ( Table 1). [39] Preliminary experiments showedt hat reproducible results were obtained with mesitylcopper(I) (MesCu) [40,41] as source of copper(I) and as base toward imidazol(in)ium salts 4 in THF.…”

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confidence: 99%

Z‐Selective Copper(I)‐Catalyzed Alkyne Semihydrogenation with Tethered Cu–Alkoxide Complexes

Pape

Thiel

Teichert

2015

Chemistry A European J

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Multicomponent Synthesis of Chiral Bidentate Unsymmetrical Unsaturated N‐Heterocyclic Carbenes: Copper‐Catalyzed Asymmetric CC Bond Formation

Cited by 59 publications

References 44 publications

Early/Late Heterobimetallic Tantalum/Rhodium Species Assembled Through a Novel Bifunctional NHC‐OH Ligand

Early/Late Heterobimetallic Tantalum/Rhodium Species Assembled Through a Novel Bifunctional NHC‐OH Ligand

Chiral N-heterocyclic Carbene Gold Complexes: Synthesis and Applications in Catalysis

Z‐Selective Copper(I)‐Catalyzed Alkyne Semihydrogenation with Tethered Cu–Alkoxide Complexes

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