Mesoionic carbenes: Reactions of 1,3‐diphenyltetrazol‐5‐ylidene with electron‐deficient alkenes, and synthesis and catalytic activities of the (tetrazol‐5‐ylidene)rhodium(I) complexes

Araki, Shuki; Yokoi, Keisaku; Sato, Ryosuke; Hirashita, T.; Setsune, Jun‐ichiro

doi:10.1002/jhet.61

Cited by 21 publications

(26 citation statements)

References 23 publications

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“…The reaction of tetrazolium salt 464 with [Rh(COD)Cl] 2 in the presence of a mild base affords a mixture of two products, namely, the neutral monotetrazolylidene rhodium(I) complex 465 and the cationic bis(tetrazolylidene) rhodium(I) complexes 466 (Scheme ). Bond lengths and angles are not different from analogous complexes with Arduengo-type 2-imidazolylidene ligands. These complexes catalyze the decarbonylative addition reaction of benzoyl chloride to ethynylbenzene (Scheme ).…”

Section: Complexes With Other 5-membered N-heterocyclic Carbene Ligandsmentioning

confidence: 99%

Mesoionic and Related Less Heteroatom-Stabilized N-Heterocyclic Carbene Complexes: Synthesis, Catalysis, and Other Applications

2018

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Mesoionic carbenes are a subclass of the family of N-heterocyclic carbenes that generally feature less heteroatom stabilization of the carbenic carbon and hence impart specific donor properties and reactivity schemes when coordinated to a transition metal. Therefore, mesoionic carbenes and their complexes have attracted considerable attention both from a fundamental point of view as well as for application in catalysis and beyond. As a follow-up of an earlier Chemical Reviews overview from 2009, the organometallic chemistry of N-heterocyclic carbenes with reduced heteroatom stabilization is compiled for the 2008-2017 period, including specifically the chemistry of complexes containing 1,2,3-triazolylidenes, 4-imidazolylidenes, and related 5-membered N-heterocyclic carbenes with reduced heteratom stabilization such as (is)oxazolylidenes, pyrrazolylidenes, and thiazolylidenes, as well as pyridylidenes as 6-membered N-heterocyclic carbenes with reduced heteroatom stabilization. For each ligand subclass, metalation strategies, electronic and steric properties, and applications, in particular, in metal-mediated catalysis, are compiled. Mesoionic carbenes demonstrate particularly high activity in (water) oxidation, hydrogen transfer reactions, and cyclization reactions. Unique features of these ligands are identified such as their dipolar structure, their specific donor properties, as well as stability aspects of the ligand and the complexes, which provides opportunities for further research.

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Section: Complexes With Other 5-membered N-heterocyclic Carbene Ligandsmentioning

confidence: 99%

Mesoionic and Related Less Heteroatom-Stabilized N-Heterocyclic Carbene Complexes: Synthesis, Catalysis, and Other Applications

2018

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“…This determines the single/double-bond arrangement in tetrazole rings of 5 and 6′ , drawn in Scheme . Such bond allocation is typical for 1,4,5- , and 1,3,5-trisubstituted , tetrazoles. All other bonds and angles are of normal values.…”

Section: Resultsmentioning

confidence: 89%

Borylated Tetrazoles from Cycloaddition of Azide Anions to Nitrilium Derivatives ofcloso-Decaborate Clusters

Mindich

Bokach

Kuznetsov³

et al. 2013

Organometallics

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Interaction of the closo-decaborate clusters [Bu n 4 N][B 10 H 9 (NCR)] (R = Me 1a, Et 1b, Bu t 1c, Ph 1d) with the azide [Ph 3 PNPPh 3 ]N 3 proceeds immediately upon mixing the reagents in an MeCN solution at RT, giving the borylated 1,5-disubstituted tetrazoles [B 10 H 9 (N 4 CR)] 2− in essentially quantitative yield. On a synthetic scale, sodium azide, NaN 3 , reacts similarly with the nitrile functionality of 1a−d in an acetonitrile suspension under mild conditions (RT, 15 h) to afford selectively the borylated tetrazoles [Bu n 4 N] 2 [B 10 H 9 (N 4 CR)] (2a−d; 88−96% isolated yields) and the water-soluble Na 2 [B 10 H 9 (N 4 CR)] species (3a−d; ca. 95% isolated yield) after the metathetical reaction with NaBPh 4 in MeOH/H 2 O. The reaction with N 3 − represents the first example of the propargyl-allenyl anion type dipole cycloaddition (CA) to the nitrilium derivatives of any boron clusters. Reactions of 1a−d with alkyl or aryl azides (p-Me-C 6 H 4 -COCH 2 N 3 , p-NO 2 -C 6 H 4 -CH 2 N 3 , PhN 3 ) do not proceed even under harsh conditions (2 d, dry EtCN, 100 °C, under Ar). However, corresponding 1,4,5-trisubstituted tetrazoles 4a−d, 5, and 6 and 1,3,5-isomers 4′a−d, 5′, and 6′ were obtained by alkylation of 2a−d. The isomers were separated by column chromatography and identified by 2D NOESY NMR and X-ray crystallography (for 5 and 6′). Compounds 2a− d, 3a−d, 4a,b, 4′a−d, 5, 6, 5′, and 6′ were characterized by ICP-MS-based B analysis, high-resolution ESI-MS, molar conductivity, IR, and 1 H, 13 C{ 1 H}, and 11 B{ 1 H} NMR spectroscopies. The structures of 2c, 5, and 6′ were elucidated by single-crystal X-ray diffraction. Theoretical calculations at the DFT level (B3LYP and M06-2X functionals) allowed the establishment of the reaction mechanism, which is stepwise in the case of the azide-ion CA and concerted asynchronous (by 30−43%) for the hypothetical CA of RN 3 . The higher reactivity of N 3 − toward the borylated nitriles in comparison with organic azides RN 3 (by 10.8−18.7 kcal/mol in terms of ΔG s ⧧ values calculated at M06-2X) is mostly accounted for by the solvent effects, and these reactions are controlled by kinetic rather than thermodynamic factors.

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“…61 Tetrazol-5-ylidene rhodium complexes have been synthesized. 62 Their catalytic role proved to be similar to but less effective than that of (cod) 2 RhCl 2 in the decarbonylative addition of dibenzoylchloride to ethynylbenzene.…”

Section: Carbenes In Coordination Chemistry (Carbenes As Ligands)mentioning

confidence: 99%

“…62 A direct synthesis of 1,1 -disubstituted biscyclopropanes from propargylic alcohols has been reported. 74 It is conveniently carried out by action of trialkylaluminium and diiodomethane and labelling experiments have provided some support for a mechanism involving an aluminium carbenoid.…”

Section: Free Carbenes or Main Group Carbenoids Reactionsmentioning

confidence: 99%

Carbenes and Nitrenes

Gras

Chassaing

2011

Organic Reaction Mechanisms Series

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Mesoionic carbenes: Reactions of 1,3‐diphenyltetrazol‐5‐ylidene with electron‐deficient alkenes, and synthesis and catalytic activities of the (tetrazol‐5‐ylidene)rhodium(I) complexes

Cited by 21 publications

References 23 publications

Mesoionic and Related Less Heteroatom-Stabilized N-Heterocyclic Carbene Complexes: Synthesis, Catalysis, and Other Applications

Mesoionic and Related Less Heteroatom-Stabilized N-Heterocyclic Carbene Complexes: Synthesis, Catalysis, and Other Applications

Borylated Tetrazoles from Cycloaddition of Azide Anions to Nitrilium Derivatives ofcloso-Decaborate Clusters

Carbenes and Nitrenes

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