Asymmetric induction afforded by chiral azolylidene N-heterocyclic carbenes (NHC) catalysts

Strand, Ragnhild B.; Helgerud, Trygve; Solvang, Tina; Dolva, Amund; Sperger, Christian A.; Fiksdahl, Anne

doi:10.1016/j.tetasy.2012.09.004

Cited by 30 publications

(13 citation statements)

References 52 publications

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“…The two central Au(I) cations exhibit nearly linear complexing modes, with two C MIC –Au(I)–Cl angles ranged from 176.15 to 179.39°. The Au–C MIC bonds ranged from 1.986(0) to 2.032(8) Å, which is similar to the previous reported Au(I)–C bond length. − In complexes ( R )- 8a , ( R )- 8f , and ( R )- 8g , the distances between the two auric cations ranged from 4.830(6) to 5.365(6) Å, without Au(I)–Au(I) interaction.…”

Section: Resultssupporting

confidence: 86%

“…As shown in Table , the 13 C NMR spectrum of complexes ( R )- 8a – g display the characteristic resonance at the region 158–161 ppm, which are corresponding to the Au–C MIC moiety (Table ). − The bis(MIC)-bis(Au) structures of ( R )- 8a could be deduced from their high-resolution mass spectrometry {HRMS (ESI) for [C 38 H 28 Au 2 ClN 6 ] + , calcd: 997.1401. Found: 997.1430}, which correspond to [Au 2 LCl] + .…”

Section: Resultsmentioning

confidence: 99%

“…In 2011, an axially chiral N -heterocyclic carbene gold(I) complex was developed by Shi’s group and was applied in 1,6-enyne’s asymmetric cycloisomerization reaction (Scheme B) . Thereafter, a variety of axially chiral NHC–Au(I) complexes, which contained different ligands, including imidazol-2-ylidenes, 1,2,4-triazol-5-ylidenes, and diaminocarbenes, have been developed by the groups of Kündig, Shi, Mascareñas, Espinet, Toste, ,, and Slaughter (Scheme A,B) . Specifically, Toste’s group recently reported a chiral NHC bearing Au(III) catalyst to catalyze 1,5-enyne’s enantioconvergent kinetic resolution (Scheme C) …”

Section: Introductionmentioning

confidence: 99%

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Synthesis of Axially Chiral 1,2,3-Triazol-5-ylidene–Au(I) Complex and Its Application in Enantioselective [2 + 2] Cycloaddition of Alleneamides with Alkenes

et al. 2018

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A series of axially chiral bis-1,2,3-triazol-5-ylidene Au(I) complexes (R)-8a–g and one mono-1,2,3-triazol-5-ylidene Au(I) complex (R)-9a were prepared from commercially available (R)-binaphthyl-2,2-diamine (BINAM) compound, in which, transmetalation of bis(MIC)-bis[Ag(I)] intermediates to the corresponding Au(I) complexes were employed as the key synthetic step. The structures of these MIC–Au(I) complexes were diversified by using different alkyne reagents in copper catalyzed azide–alkyne cycloaddition (CAAC) step. Three chiral bis-1,2,3-triazol-5-ylidene Ag(I) complexes, (R)-7a, (R)-7c, and (R)-7d, were prepared and fully characterized. On the basis of (R)-7a’s crystal structure, a chiral tetra(MIC)-bis(Ag) structure was exhibited, with two chiral bis-1,2,3-triazol-5-ylidene ligands interconnected by two nearly linear silver atom bridges, of which, significant Ag(I)–Ag(I) bonding existed. The crystal structures of (R)-8a, (R)-8f, and (R)-8g were also obtained, which exhibit an axially chiral bis(MIC)-bis(Au) structure without Au(I)–Au(I) interaction. Application of these axially chiral bis-/mono- 1,2,3-triazol-5-ylidene Au(I) complexes in the enantioselective [2 + 2] cycloaddition of alleneamides 10a with p-methoxy styrene 11a were explored, in which (R)-8b with p-methoxy phenyl substituent performed better than other Au(I) complexes. Various substrate scopes, including different alleneamides and mono-, bisubstituted olefins were investigated by using (R)-8b/AgSbF6 catalyst combination. It was found that product’s enantioselectivities are highly dependent upon substrate’s structure, especially in the reactions of acyclic allenesulfoamide substrates. Most of the chiral cyclobutane product’s enantioselectivities ranged from 61 to 99% ee. The [2 + 2] cycloaddition of 2,3-dimethylindole 13 with alleneamide 10a was also explored by using (R)-8b and (R)-8g as the catalyst precursors.

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Section: Resultssupporting

confidence: 86%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synthesis of Axially Chiral 1,2,3-Triazol-5-ylidene–Au(I) Complex and Its Application in Enantioselective [2 + 2] Cycloaddition of Alleneamides with Alkenes

et al. 2018

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“…New chiral imidazolium-and triazolium-based gold(I)-NHC catalysts were tested, with poor results, in the intermolecular reaction of propargyl and enol esters (Scheme 87). 193 Although the chiral induction was low (< 28% ee), these results represent the first reported chiral gold(I)-NHC-catalyzed alkene cyclopropanation.…”

Section: Scheme 84mentioning

confidence: 69%

Asymmetric Cyclopropanation Reactions

2014

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Both physical and organic chemists are interested in the cyclopropane ring, the former owing to the strain inherent to the small ring structure, the latter prompted by the importance of this ring in naturally occurring compounds. In recent years, the increasing interest in enantioselective organic synthesis has led to a large number of papers on the preparation of cyclopropane compounds in enantioenriched form. The last review on asymmetric cyclopropanation reactions is dated 2008, thus an update is necessary with critical comparison of preparations using chiral auxiliaries, chiral metal complexes and organocatalysts. The aim of this review is an overview of these topics from 2008 to mid-2013.

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“…Strand et al. reported three Au(I) complexes, 169 – 171 (Figure ), of chiral NHC ligands prepared by a one‐pot transmetallation protocol using the corresponding Ag(I) complexes and evaluated their performance in asymmetric cyclopropanation . The olefin cyclopropanation using an ester‐substituted terminal alkyne and an olefin resulted in the formation of cis‐ and trans ‐cyclopropane‐substituted olefins as depicted in Scheme .…”

Section: Au(i)‐carbene Complexes Of Chiral Nhc Ligandsmentioning

confidence: 99%

Coinage Metal Complexes of Chiral N‐Heterocyclic Carbene Ligands: Syntheses and Applications in Asymmetric Catalysis

et al. 2020

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Chiral N‐heterocyclic carbenes (NHCs) have become ligands of choice due to their remarkable catalytic activity in organic transformation reactions. Combining the chiral NHC ligand family and coinage metals became a productive area of research. The organometallic chemistry of coinage metals with the chiral N‐heterocyclic carbene (NHC) ligands is reviewed, with a special emphasis on the synthesis, characterization and possible applications obtained. Significant sections are devoted to the various recently developed coinage metal‐chiral NHC complexes and a detailed comparison of their activities which aims to rationalize the structure–activity relationships. Various methods of preparations of coinage metal‐chiral NHC complexes along with some typical examples of reactivity and mechanisms are covered. Cu‐chiral NHC complexes involved in conjugated additions, allylic substitutions, boration of alkenes, hydrosilylation of ketones and formation of alkenes are covered, along with some remarkable examples and reactivity of Ag‐chiral NHC complexes. Finally, applications of Au‐chiral NHC complexes in the asymmetric cyclization of ester‐functionalized 1,6‐enynes, 1,6‐enyneamines and substituted propargyloxymethanes are also reviewed.

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Asymmetric induction afforded by chiral azolylidene N-heterocyclic carbenes (NHC) catalysts

Cited by 30 publications

References 52 publications

Synthesis of Axially Chiral 1,2,3-Triazol-5-ylidene–Au(I) Complex and Its Application in Enantioselective [2 + 2] Cycloaddition of Alleneamides with Alkenes

Synthesis of Axially Chiral 1,2,3-Triazol-5-ylidene–Au(I) Complex and Its Application in Enantioselective [2 + 2] Cycloaddition of Alleneamides with Alkenes

Asymmetric Cyclopropanation Reactions

Coinage Metal Complexes of Chiral N‐Heterocyclic Carbene Ligands: Syntheses and Applications in Asymmetric Catalysis

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