Boron‐Catalyzed Carbonate Functionality Transfer Reaction

Rao, Santhosh; Ashwathappa, Puneeth Kumar Someswara; Prabhu, Kandikere Ramaiah

doi:10.1002/ajoc.201800751

Cited by 13 publications

(13 citation statements)

References 23 publications

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“…The electrophilic carbene center of the diazoester reacted with nucleophilic carbonates to afford the dialkylated carbonate compounds in good to excellent yields (up to 96%, 15 examples). 9 It is presumed that the tert -butyl group is eliminated as isobutylene.…”

Section: Azide/carbamate Insertionmentioning

confidence: 99%

“…While metals have the ability to undergo synergic bonding and back-bonding interactions with the carbene intermediates, this is not the case for triarylboranes in which the central boron center behaves purely as an acceptor into the vacant p-orbital. 6 Using fluorinated triarylboranes [B(Ar F ) 3 ], a range of carbene transfer reactions have been achieved including O−H/N−H/ C−H insertion, 7 azide transfer, 8 carbonate transfer, 9 CC bond formation, 10 carbocycle formation (cyclopropanation/ cyclopropenation), 7c,11 and the ring opening of heterocyclic compounds. 7c In this perspective, we will discuss the activation of diazo compounds toward N 2 release followed by the subsequent reactions of the carbene-borane bound intermediate in both stoichiometric and catalytic reactions.…”

Section: ■ Introductionmentioning

confidence: 99%

“…Using fluorinated triarylboranes [B(Ar F ) 3 ], a range of carbene transfer reactions have been achieved including O–H/N–H/C–H insertion, azide transfer, carbonate transfer, CC bond formation, carbocycle formation (cyclopropanation/cyclopropenation), , and the ring opening of heterocyclic compounds . In this perspective, we will discuss the activation of diazo compounds toward N 2 release followed by the subsequent reactions of the carbene-borane bound intermediate in both stoichiometric and catalytic reactions.…”

Section: Introductionmentioning

confidence: 99%

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Triarylborane Catalyzed Carbene Transfer Reactions Using Diazo Precursors

2021

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Reactive carbenes generated from diazo compounds are key intermediates for a range of organic reactions to afford synthetically useful organic compounds. The majority of these reactions have been carried out using transition metal catalysts. However, the formation of carbene intermediates using main group elements has not been widely investigated for synthetic purposes. Recent studies have demonstrated that triarylboranes can be used for the in situ generation of reactive carbene intermediates in both stoichiometric and catalytic reactions. These new reactivities of triarylboranes have gained significant attention in synthetic chemistry particularly in catalytic studies. The range of organic compounds that have been synthesized through these reactions are important as pharmaceuticals or agrochemicals. In this perspective, we highlight the recent progress and ongoing challenges of carbene transfer reactions generated from their corresponding diazo precursors using triarylboranes as catalysts. We also highlight the stoichiometric use of triarylboranes in which the boranes not only activate the diazo functionality to afford a carbene intermediate but also actively participate in the reactions as a reagent. The different mechanisms for activation and carbene transfer are described along with the mechanistic and computational studies that have aided the elucidation of these reaction pathways. Potential opportunities for the use of boranes as a catalyst toward different carbene transfer reactions and their future prospects are discussed.

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Section: Azide/carbamate Insertionmentioning

confidence: 99%

Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Triarylborane Catalyzed Carbene Transfer Reactions Using Diazo Precursors

2021

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“…Kürzlich haben wir [5] und andere [6a] die katalytische Aktivität von B(C 6 F 5 ) 3 bei der Aktivierung von Diazoestern untersucht, die zur Bildung von Carben‐Zwischenprodukten durch die Abspaltung von N 2 führt. Die Carben‐Zwischenprodukte können anschließend als Bausteine für die Synthese neuartiger organischer Moleküle durch eine Reihe verschiedener Reaktionen wie O‐H/N‐H/C‐H‐Insertion, [5a, 6b,d,g,h] Azid/Carbonat‐Transfer, [6e,f] Cyclopropanierung/Cyclopropenierung [5a, 6c] und für die Ringöffnung heterocyclischer Verbindungen verwendet werden [5a] . In dieser Studie interessierten wir uns für die B(C 6 F 5 ) 3 ‐katalysierte Synthese von Pyrazolen aus Vinyldiazoacetaten, bei der die N 2 ‐Funktionalität des Diazo‐Ausgangsmaterials nicht freigesetzt wird.…”

Section: Methodsunclassified

Tris(pentafluorphenyl)boran‐katalysierte Erzeugung von Carbenium‐Ionen und autokatalytische Pyrazol‐Synthese – eine theoretische und experimentelle Studie

Dasgupta

Babaahmadi²,

Pahar

et al. 2021

Angewandte Chemie

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In recent years, metal-free organic synthesis using triarylboranes as catalysts has become a prevalent research area. Herein we report a comprehensive computational and experimental study for the highly selective synthesis of Nsubstituted pyrazoles through the generation of carbenium species from the reaction between aryl esters and vinyl diazoacetates in the presence of catalytic tris(pentafluorophenyl)borane [B(C 6 F 5 ) 3 ]. DFT studies were undertaken to illuminate the reaction mechanism revealing that the in situ generation of a carbenium species acts as an autocatalyst to prompt the regiospecific formation of N-substituted pyrazoles in good to excellent yields (up to 81 %).

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“…[4] Recently ourselves, [5] and others [6a] have explored the catalytic activity of B(C 6 F 5 ) 3 in the activation of diazoesters leading to the formation of carbene intermediates through the elimination of N 2 . The carbene intermediate can subsequently be used as building block for the synthesis of novel organic molecules through a range of different reactions such as O−H/N−H/C−H insertion,[ 5a , 6b , 6d , 6g , 6h ] azide/carbonate transfer,[ 6e , 6f ] cyclopropanation/cyclopropenation,[ 5a , 6c ] and the ring‐opening of heterocyclic compounds. [5a] In this study, we were interested in the B(C 6 F 5 ) 3 ‐catalyzed synthesis of pyrazoles from vinyl diazoacetates in which the N 2 functionality of the diazo starting material is not released.…”

mentioning

confidence: 99%