Intrinsically Safe and Shelf-Stable Diazo-Transfer Reagent for Fast Synthesis of Diazo Compounds

Xie, Shibo; Yan, Ziqiang; Li, Yuanheng; Song, Qun; Ma, Mingming

doi:10.1021/acs.joc.8b01587

Cited by 24 publications

(29 citation statements)

References 29 publications

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“…Based on our primary investigation and previous reports, , a plausible catalytic cycle can be proposed (Scheme ). In the presence of pivalic acid, the active catalyst A is formed.…”

Section: Resultsmentioning

confidence: 97%

“…To find a fruitful and benign catalyst system for the synthesis of chromone, herein, we developed an Ir(III)-catalyzed C–H bond functionalization in water medium. To include versatility in this annulation process, we have incorporated differently substituted salicylaldehydes and α-diazo carbonyls . Relatively low catalyst loading, short reaction time, and the use of ubiquitous and inexpensive water as a solvent for Ir(III)-catalyzed C–H bond functionalization are main advantages of our present catalytic system.…”

Section: Introductionmentioning

confidence: 99%

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On-Water Cp*Ir(III)-Catalyzed C–H Functionalization for the Synthesis of Chromones through Annulation of Salicylaldehydes with Diazo-Ketones

Debbarma

Modak

et al. 2019

J. Org. Chem.

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A high-valent Ir(III)-catalyzed C−H bond functionalization is carried out for the first time on water for the synthesis of a biologically relevant chromone moiety. The C−H activation and annulation of salicylaldehydes with diazocompounds provided the desired chromones. The synthesis of C3-substitution-free chromones has also been demonstrated by a one-pot decarboxylation by employing tert-butyl diazoester. C3 and C5 C−H activations of the product chromone are also carried out under different conditions for further diversification.

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“…Based on our primary investigation and previous reports, , a plausible catalytic cycle can be proposed (Scheme ). In the presence of pivalic acid, the active catalyst A is formed.…”

Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

On-Water Cp*Ir(III)-Catalyzed C–H Functionalization for the Synthesis of Chromones through Annulation of Salicylaldehydes with Diazo-Ketones

Debbarma

Modak

et al. 2019

J. Org. Chem.

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“…This was shown to be effective in the transfer of N2 to a variety of activated methylene positions (Figure 1 and Scheme 1). 16 The reaction was reported to proceed rapidly in DMSO using various bases, and achieved excellent yields of diazo compounds with a variety of substrates. We observed similarly successful results with this reagent.…”

Section: Figure 1 Selected Diazo Transfer Reagentsmentioning

confidence: 99%

“…ADT was prepared in one step from 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) or in two steps from 2,4,6-trichloro-1,3,5triazine (TCT) as reported by Ma (Scheme 2). 16 Both the intermediate CDMT and precursor TCT are commercially available peptide coupling reagents. DSC analysis on TCT and CDMT was recently reported by Pfizer and neither was considered to be potentially impact sensitive or explosive (For TCT: Tinit = 360 °C, ΔHD = -36 J g -1 ; For CDMT: Tinit = 161 °C and ΔHD = -513 J g -1 ).…”

Section: Scheme 1 Diazo Transfer Reaction With Adtmentioning

confidence: 99%

Diazo-Transfer Reagent 2-Azido-4,6-dimethoxy-1,3,5-triazine Displays Highly Exothermic Decomposition Comparable to Tosyl Azide

et al. 2019

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2-Azido-4,6-dimethoxy-1,3,5-triazine (ADT) was reported recently as a new 'intrinsically safe' diazo transfer reagent. This assessment was based on Differential Scanning Calorimetry (DSC) data indicating that ADT exhibits endothermic decomposition. We present DSC data on ADT that show exothermic decomposition with an initiation temperature (Tinit) of 159 °C and an enthalpy of decomposition (ΔHD) of-1135 J g-1 (-207 kJ mol-1). We conclude that ADT is potentially explosive and must be treated with caution, being of comparable exothermic magnitude to tosyl azide (TsN3). A maximum recommended process temperature for ADT is 55 °C. Diazo transfer reagents effect the transfer of N2 to activated methylene substrates and amines to generate diazo and azide compounds respectively. Although a range of organoazide diazo transfer reagents exist (Figure 1), sulfonyl azides are the most widely used. 1 Sulfonyl azides are, however, highly energetic due to the thermodynamically favourable formation of gaseous decomposition products, and some are reported to be impact sensitive and potentially explosive. 2,3 Improving the safety profile of diazo transfer reagents has been a key driver in this field since the initial use of tosyl azide (TsN3) over 50 years ago. 4 parts per million with the residual protic solvent resonance as the internal standard (chloroform: 7.27 ppm). Data were reported as follows: chemical shift (multiplicity, integration). 13 C NMR spectra were recorded with complete proton decoupling. Chemical shifts are reported in parts per million with the solvent resonance as the internal standard (13 CDCl3: 77.0 ppm).

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“…The N 2 transfer is typically effected by sulfonyl azide reagents, though recently, other azides have been developed that effect the same reaction. 54,55 Sulfonyl azides are commonly used diazo transfer reagents that have known hazardous properties. 56 Several explosions have been reported, 57−61 and so, these compounds have been relatively well studied.…”

Section: ■ Introductionmentioning

confidence: 99%

Thermal Stability and Explosive Hazard Assessment of Diazo Compounds and Diazo Transfer Reagents

Green

Wheelhouse

Payne

et al. 2019

Org. Process Res. Dev.

181

200

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Despite their wide use in academia as metal-carbene precursors, diazo compounds are often avoided in industry owing to concerns over their instability, exothermic decomposition, and potential explosive behavior. The stability of sulfonyl azides and other diazo transfer reagents is relatively well understood, but there is little reliable data available for diazo compounds. This work first collates available sensitivity and thermal analysis data for diazo transfer reagents and diazo compounds to act as an accessible reference resource. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and accelerating rate calorimetry (ARC) data for the model donor/acceptor diazo compound ethyl (phenyl)diazoacetate are presented. We also present a rigorous DSC dataset with 43 other diazo compounds, enabling direct comparison to other energetic materials to provide a clear reference work to the academic and industrial chemistry communities. Interestingly, there is a wide range of onset temperatures (T onset ) for this series of compounds, which varied between 75 and 160 °C. The thermal stability variation depends on the electronic effect of substituents and the amount of charge delocalization. A statistical model is demonstrated to predict the thermal stability of differently substituted phenyl diazoacetates. A maximum recommended process temperature (T D24 ) to avoid decomposition is estimated for selected diazo compounds. The average enthalpy of decomposition (ΔH D ) for diazo compounds without other energetic functional groups is −102 kJ mol −1 . Several diazo transfer reagents are analyzed using the same DSC protocol and found to have higher thermal stability, which is in general agreement with the reported values. For sulfonyl azide reagents, an average ΔH D of −201 kJ mol −1 is observed. High-quality thermal data from ARC experiments shows the initiation of decomposition for ethyl (phenyl)diazoacetate to be 60 °C, compared to that of 100 °C for the common diazo transfer reagent p-acetamidobenzenesulfonyl azide (p-ABSA). The Yoshida correlation is applied to DSC data for each diazo compound to provide an indication of both their impact sensitivity (IS) and explosivity. As a neat substance, none of the diazo compounds tested are predicted to be explosive, but many (particularly donor/acceptor diazo compounds) are predicted to be impact-sensitive. It is therefore recommended that manipulation, agitation, and other processing of neat diazo compounds are conducted with due care to avoid impacts, particularly in large quantities. The full dataset is presented to inform chemists of the nature and magnitude of hazards when using diazo compounds and diazo transfer reagents. Given the demonstrated potential for rapid heat generation and gas evolution, adequate temperature control and cautious addition of reagents that begin a reaction are strongly recommended when conducting reactions with diazo compounds.

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Intrinsically Safe and Shelf-Stable Diazo-Transfer Reagent for Fast Synthesis of Diazo Compounds

Cited by 24 publications

References 29 publications

On-Water Cp*Ir(III)-Catalyzed C–H Functionalization for the Synthesis of Chromones through Annulation of Salicylaldehydes with Diazo-Ketones

On-Water Cp*Ir(III)-Catalyzed C–H Functionalization for the Synthesis of Chromones through Annulation of Salicylaldehydes with Diazo-Ketones

Diazo-Transfer Reagent 2-Azido-4,6-dimethoxy-1,3,5-triazine Displays Highly Exothermic Decomposition Comparable to Tosyl Azide

Thermal Stability and Explosive Hazard Assessment of Diazo Compounds and Diazo Transfer Reagents

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