B(C6F5)3-catalyzed Wolff rearrangement/[2 + 2] and [4 + 2] cascade cyclization of α-diazoketones with imines

Song, Weihong; Guo, Jing; Stephan, Douglas W.

doi:10.1039/d3qo00054k

Cited by 9 publications

(4 citation statements)

References 41 publications

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“…In 2023, Stephan and co-workers reported [2+4] and [2+2] cascade cyclization reactions starting from N-protected imines and -diazo ketones using B(C 6 F 5 ) 3 as a catalyst (Scheme 17). 21 Importantly, by altering the N-protecting group in the imine, different reactivity was observed. When N-tert-butoxycarbonyl imines were reacted with -diazo ketones, a series of -lactams were synthesized via a [2+2] cascade cyclization process.…”

Section: Short Review Synthesismentioning

confidence: 99%

“…The binding sites of the borane with the diazo compound and the mode of N 2 release are also discussed. We have catalogued the reactions by reaction type including O-H, 10 N-H, 11,12 S-H, 13 and C-H insertions, 14,15 azide insertion, 16 carbonate transfer, 17 C-C and C=C bond-forming reactions, 18,19 cascade reactions, 20,21 and annulation reactions, 22,23 by utilizing diazo compounds as a carbene synthon in the presence of the borane B(C 6 F 5 ) 3 as a metal-free catalyst.…”

Section: Short Review Synthesismentioning

confidence: 99%

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Activation of Diazo Compounds by Fluorinated Triarylborane Catalysts

Pramanik

Melen

2023

Synthesis

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The diverse applicability of diazo compounds as versatile reagents has enlarged the chemical toolbox in organic synthesis. Over the past few decades, transition metal-catalyzed diazo compound activation has ignited the classical synthetic methodology via utilizing highly reactive metal carbenoid species. Many reviews have also appeared in the literature which discloses the advantage and disadvantages of metal-catalyzed activation of the diazo compound. Recently, tris(pentafluorophenyl) borane-mediated diazo activation reactions have reconciled this research area due to the potential for mild, environmentally-friendly, metal-free, non-toxic reaction conditions, and the diverse reactivity patterns of boranes towards diazo compounds. In this review, we have discussed the reactivity of the boron-diazo precursor adduct with compounds using catalytic and stoichiometric halogenated triarylboranes and, the mechanism of N2 release from the diazo reagent. This generates the reactive carbene species as a key intermediate which can further be exploited for O−H, N−H, S‒H, and C−H insertions, azide insertion, carbonate transfer, C‒C and C=C bond forming reactions, [2+2] or [2+4] cascade cyclization reactions, annulation reactions, etc. This review is classified by the following themes: 1. Introduction 2. Diazo Activation Using Stoichiometric Boranes 3. Diazo Activation Using Catalytic B(C6F5)3 4. B(C6F5)3 Catalyzed Diazo Activation Reactions 5. Conclusions

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Section: Short Review Synthesismentioning

confidence: 99%

Section: Short Review Synthesismentioning

confidence: 99%

Activation of Diazo Compounds by Fluorinated Triarylborane Catalysts

Pramanik

Melen

2023

Synthesis

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“…11 Moreover, B(C 6 F 5 ) 3 also catalyzed [2 + 2] and [4 + 2] of imines with diazoketones. 12 Furthermore, B(C 6 F 5 ) 3 catalyzed cyclopropanation of 3-alkenyl-oxindoles with diazomethanes (Scheme 1a). 13 This reaction afforded a route to spirocyclopropane-oxindoles.…”

mentioning

confidence: 99%

“…Altering the solvent to chloroform (CHCl 3 ), 1,2-dichloroethane (1,2-DCE), toluene, n-hexane and Et 2 O revealed that CH 2 Cl 2 and CHCl 3 gave similar results while use of the other solvents reduced the yield of 1 somewhat (entries 6-11). Variation of the catalyst loading and the A : B ratio showed that the optimized conditions involved the use of excess methyl 4-bromophenyl diazoacetate in the presence of 1 mol% of B(C 6 F 5 ) 3 as this afforded the near quantitative yield of 1 (entries [12][13][14][15].…”

mentioning

confidence: 99%

Borane catalyzed transesterification of tert-butyl esters using α-aryl α-diazoesters

Yan,

Xiao,

Xiong

et al. 2023

Org. Biomol. Chem.

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DFT Study in an Asymmetric Organocatalytic Homologation: Mechanism, Origin of Stereoselectivity

Wang,

Wei

2024

Asian J Org Chem

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In the present study, the mechanism, origin of stereoselectivity, and role of catalyst of the organocatalytic homologation reaction between phenyl boronate and trifluoromethyl diazomethane have been theoretically investigated using the density functional theory (DFT) method. Based on the calculations, the in situ generated ethanol plays significant role in triggering the reaction. Moreover, the [1,2]‐boron migration process is the stereoselectivity‐determining step, with the S‐configured isomer being generated predominantly. In addition, NCI analysis is performed to disclose the origin of stereoselectivity.

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B(C₆F₅)₃-catalyzed Wolff rearrangement/[2 + 2] and [4 + 2] cascade cyclization of α-diazoketones with imines

Abstract: B(C6F5)3 is shown to catalyze the reactions of carbonyl imines with α-diazoketones by initiating a Wolff Rearrangement followed by a subsequent cyclization. However, variations in the N-protecting groups of imines...

Cited by 9 publications

References 41 publications

Activation of Diazo Compounds by Fluorinated Triarylborane Catalysts

Activation of Diazo Compounds by Fluorinated Triarylborane Catalysts

Borane catalyzed transesterification of tert-butyl esters using α-aryl α-diazoesters

DFT Study in an Asymmetric Organocatalytic Homologation: Mechanism, Origin of Stereoselectivity

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