Mechanism of the Gold(III)-Catalyzed Isomerization of Substituted Allenes to Conjugated Dienes: A DFT Study

Basak, Atanu; Chakrabarty, Kuheli; Ghosh, Animesh; Das, Gourab Kanti

doi:10.1021/jo401400x

Cited by 22 publications

(8 citation statements)

References 105 publications

(67 reference statements)

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“…DFT calculations (PBE0/6-31G**/(aug)-ccpVDZ) by the same group 107 suggest that the Au(III)-catalysed isomerisation of substituted allene 73 to conjugated diene 77 (Scheme 12) takes place through activation of the allene by Au(III), followed by migration assisted by an additive (nitroso compound) of the hydrogen atom from the substituent alkyl group of the allene moiety to its central sp-hybridized carbon atom. The unbound nitroso compound acts as a better proton transferring agent in the isomerization process and utilizes its own nitrogen atom to carry the proton.…”

Section: Activation Of the Allene By An Electrophilic Metalmentioning

confidence: 99%

Allenes and computational chemistry: from bonding situations to reaction mechanisms

2014

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The present review is focused on the application of computational/theoretical methods to the wide and rich chemistry of allenes. Special emphasis is made on the interplay and synergy between experimental and computational methodologies, rather than on recent developments in methods and algorithms. Therefore, this review covers the state-of-the-art applications of computational chemistry to understand and rationalize the bonding situation and vast reactivity of allenes. Thus, the contents of this review span from the most fundamental studies on the equilibrium structure and chirality of allenes to recent advances in the study of complex reaction mechanisms involving allene derivatives in organic and organometallic chemistry.

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Section: Activation Of the Allene By An Electrophilic Metalmentioning

confidence: 99%

Allenes and computational chemistry: from bonding situations to reaction mechanisms

2014

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“…Computational methods have been used to shed some light on the preferred mechanisms of several reactions. [151][152][153][154][155][156] However much effort is still being dedicated to isolate some of the intermediates 56,80,94,157 and investigate the elementary steps 137,[158][159][160][161][162][163][164] proposed with either experimental or computational methods. 74,165 Coordination of olefins to gold(III) is assumed to be a key step in the catalytic functionalisation of olefins, 56,94 followed by the addition of a nucleophile.…”

Section: Mechanistic Investigationsmentioning

confidence: 99%

Versatile Methods for Preparation of New Cyclometalated Gold(III) Complexes

et al. 2012

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The interest in organogold compounds continues to grow. Gold(III) complexes are being investigated as catalysts for organic transformations as well as tested as potential anti-cancer drugs. Despite this wide-ranging interest in the properties of such complexes, the synthetic methods for preparing them are underdeveloped. Thus, Chapter 2 discusses the synthesis of cyclometalated gold(III) complexes bearing the C-N chelating ligand 2-(p-tolyl)pyridine (tpy). Monoalkylation andarylation were possible by use of Grignard reagents, whereas alkyl and aryl lithium reagents gave the dialkylated and diarylated gold(III) complexes. By a combination of the two alkylation procedures, mixed alkyl/aryl complexes of the type AuMePh(tpy) were obtained and both isomers were available. Chapter 3 discusses the reactivity of the cyclometalated gold(III) complexes towards different gases such as carbon monoxide and oxygen. Most of the cyclometalated gold(III) complexes prepared react with acids. The monoalkylated and-arylated complexes of the type AuBrR(tpy) (R = Me, Et, CHCH 2 , CCH, Ph) react with silver(I) salts to give a potential open coordination site at gold(III). Ethylene formally inserts into the Au-O bond trans to nitrogen in the chelating C-N ligand of the complex Au(OCOCF 3) 2 (tpy) (62) in trifluoroacetic acid or dichloromethane, to yield Au(CH 2 CH 2 OCOCF 3)(OCOCF 3)(tpy) (94). In trifluoroethanol, a slightly different complex resulted due to nucleophilic attack by trifluoroethanol rather than trifluoroacetate, Au(CH 2 CH 2 OCH 2 CF 3)(OCOCF 3)(tpy) (95). The mechanism of the insertion was investigated experimentally as well as computationally and the results are discussed in Chapter 4. The formal insertion takes place with alkenes other than ethylene, and alkynes react too. A key step in the catalytic reactions involving gold(III) is assumed to be the coordination of a CC multiple bond to the gold centre. Various catalytic cycles involving a gold(III) π-complex have been proposed. However, gold(III) alkene, alkyne, allene, or arene complexes have until recently not been conclusively detected and characterised. Chapter 5 discusses the first, and thus far only, crystallographically characterised gold(III) alkene complex, Au(cod)Me 2 BArF (133-BArF, BArF = tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, cod = 1,5-cyclooctadiene).

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“…12 While choosing the proper functional to carry out the search for stationary points, we were motivated by our previous success of the study on other metal-catalyzed reactions. 13 Our previous experience shows that the hybrid density functional PBE0 14 gave consistent results for Aucatalyzed reactions, and its utility had already been endorsed by other reports. For selecting a favorable pathway, we presently use the same functional (equivalent to PBE1PBE) and LANL2DZ 15 basis set for metal atoms.…”

Section: ■ Computational Methodsmentioning

confidence: 71%

“…For the study of all pathways and analysis of the properties of the individual species, we have used the density functional theory quantum mechanical method implemented in the Gaussian suite . While choosing the proper functional to carry out the search for stationary points, we were motivated by our previous success of the study on other metal-catalyzed reactions . Our previous experience shows that the hybrid density functional PBE0 gave consistent results for Au-catalyzed reactions, and its utility had already been endorsed by other reports.…”

Section: Methodsmentioning

confidence: 99%

Au-Catalyzed Hexannulation and Pt-Catalyzed Pentannulation of Propargylic Ester Bearing a 2-Alkynyl-phenyl Substituent: A Comparative DFT Study

et al. 2018

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The mechanistic pathways of metal-catalyzed pentannulation and hexannulation of aromatic enediyne were studied quantum mechanically with Pt and Au salts. In agreement with the experimental facts, our result shows that the pentannulation favors over the hexannulation under Pt-catalyzed conditions and the reverse possibility favors when the Pt salt is replaced with an Au one. The Pt-catalyzed reaction involves a long-range acyl migration that follows the cyclization step. Our study reveals that such migration takes place under the assistance of a ligand of the metal atom. Moreover, the variation of aromaticity (probed by the change of the nucleus-independent chemical shift (0) value) in the cyclization steps shows that both processes maintain the development of the aromatic character of the generated intermediate during the progress of the reaction.

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Mechanism of the Gold(III)-Catalyzed Isomerization of Substituted Allenes to Conjugated Dienes: A DFT Study

Cited by 22 publications

References 105 publications

Allenes and computational chemistry: from bonding situations to reaction mechanisms

Allenes and computational chemistry: from bonding situations to reaction mechanisms

Versatile Methods for Preparation of New Cyclometalated Gold(III) Complexes

Au-Catalyzed Hexannulation and Pt-Catalyzed Pentannulation of Propargylic Ester Bearing a 2-Alkynyl-phenyl Substituent: A Comparative DFT Study

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