Acyl Azide Synthesis and Curtius Rearrangements in Microstructured Flow Chemistry Systems

Sprecher, Hanspeter; Payán, M. Nieves Pérez; Weber, Michael; Yilmaz, Goekcen; Wille, Gregor

doi:10.1556/jfchem.2011.00017

Cited by 34 publications

(30 citation statements)

References 24 publications

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“…This requires some kind of positional feedback system. Although several methods for determining the position of the interface could be used (including refractive index 10 and electrical impedance 11 ), in the growing context of camera-enabled synthesis technologies 12 we have focused on the use of computervision systems, in conjunction with inexpensive and readily available web-cams, to locate a coloured interfacial float. In our previously described system, the control computer used the determined interfacial position to dynamically adjust the flow rate of the extractant-out pump (Fig.…”

Section: Tetrahedron Lettersmentioning

confidence: 99%

The continuous-flow synthesis of carbazate hydrazones using a simplified computer-vision controlled liquid–liquid extraction system

O’Brien

Cooper

Mhembere

2016

Tetrahedron Letters

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Please cite this article as: O'Brien, M., Cooper, D.A., Mhembere, P., The continuous-flow synthesis of carbazate hydrazones using a simplified computer-vision controlled liquid-liquid extraction system, Tetrahedron Letters (2016), doi: http://dx.doi.org/10.1016/j.tetlet. 2016.10.018 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Tetrahedron LettersThe continuous-flow synthesis of carbazate hydrazones using a simplified computervision controlled liquid-liquid extraction system. --- Corresponding author. e-mail: m.obrien@keele.ac.ukIn recent years, the emergence of continuous flow methodology has created new opportunities for chemical synthesis. 1 Compared with traditional batch processes, flow methods can often offer significant safety benefits, particularly for transformations involving hazardous conditions or reagents.2 Additionally, the small dimensional scales involved lead to the efficient and scaleinvariant interfacial transfer of energy and matter.3 A particularly attractive aspect of flow chemistry is the ability to incorporate inline purification stages. Solid-supported scavengers 4 and phaseswitching protocols have been extremely successful in this regard. 5 However, solid-supported chemicals can often be much more expensive than their solution phase counterparts. 6 In addition, they often give rise to significant and scale-dependent dispersion effects 7 and become depleted over time, thus requiring replacement or regeneration. This can be a time consuming operation which usually necessitates halting of the flow process. As liquids can be continuously pumped through the system, inline liquid-liquid phase separation does not suffer from this problem and, whilst dispersion cannot be eliminated, it can be controlled and rendered scale invariant.One general method of inline liquid-liquid separation used in continuous flow makes use of the selective wetting of certain materials, particularly expanded porous PTFE membranes, to separate aqueous and organic solutions. 8 We have been interested, however, in gravity-based separations of immiscible liquids based on their densities.9 This is essentially a continuous flow adaptation of the classical separating funnel. The basic concept is shown in Figure 1. A biphasic stream of immiscible liquids with differing densities will, when passed into a suitable vessel, separate vertically. The dense phase will exit the vessel through a lower exit and the light phase will exit the vessel through an upper exit. In Figure 1 the organic phase is the dense phase and the aqueous extractant is the light phase, although these roles could be switched if less dense o...

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Section: Tetrahedron Lettersmentioning

confidence: 99%

The continuous-flow synthesis of carbazate hydrazones using a simplified computer-vision controlled liquid–liquid extraction system

O’Brien

Cooper

Mhembere

2016

Tetrahedron Letters

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“…A Curtius rearrangement still has many safety issues. The use of flow can mitigate many of these (77), and including a FT IR module placed in-line, can be used to monitor the reaction (78). The approach has been used to prepare (-)-oseltamivir 2 (Scheme 17).…”

Section: Scheme 15 Preparation Of Amines From Azidesmentioning

confidence: 99%

Managing Hazardous Reactions and Compounds in Process Chemistry

Ager¹

2014

ACS Symposium Series

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“…19 Along similar lines, recent efforts have focused on the reaction of acyl azides to form isocyanates, which can then be treated with nucleophiles to form products such as amines, carbamates and amides. [20][21][22][23] Ley and co-workers utilized an azide-containing monolith in a flow system for performing the Curtius rearrangement with acid chloride precursors. 20 Wille and co-workers reported the in situ preparation of a diacyl azide as an intermediate for the Curtius rearrangement within a microreactor.…”

mentioning

confidence: 99%

“…20 Wille and co-workers reported the in situ preparation of a diacyl azide as an intermediate for the Curtius rearrangement within a microreactor. 21 Watts and coworker reported the continuous-flow synthesis of acyl azides under monophasic and biphasic regimes. 22 There are also examples of azide formation using polymer-bound and monolith azide sources.…”

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confidence: 99%

Acyl azide generation and amide bond formation in continuous-flow for the synthesis of peptides

et al. 2020

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Acyl Azide Synthesis and Curtius Rearrangements in Microstructured Flow Chemistry Systems

Cited by 34 publications

References 24 publications

The continuous-flow synthesis of carbazate hydrazones using a simplified computer-vision controlled liquid–liquid extraction system

The continuous-flow synthesis of carbazate hydrazones using a simplified computer-vision controlled liquid–liquid extraction system

Managing Hazardous Reactions and Compounds in Process Chemistry

Acyl azide generation and amide bond formation in continuous-flow for the synthesis of peptides

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