Azide monoliths as convenient flow reactors for efficient Curtius rearrangement reactions

Baumann, Marcus; Baxendale, Ian R.; Ley, Steven V.; Nikbin, Nikzad; Smith, Christopher D.

doi:10.1039/b801634h

Cited by 117 publications

(74 citation statements)

References 60 publications

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“…31 Under flow conditions the rearrangement to the isocyanate was initiated which was trapped with different nucleophiles such as ethanol to yield carbamates like 32 (Scheme 8).…”

Section: This Journal Is C the Royal Society Of Chemistry 2011mentioning

confidence: 99%

Ten key issues in modern flow chemistry

2011

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He studied chemistry at the Leibniz University Hannover where he received his diploma degree in 2008. He is currently performing his doctoral studies at Hannover under the supervision of Prof. Andreas Kirschning with the aid of a scholarship by the Fonds der Chemischen Industrie. In 2010 he spent several months in the group of Prof. S. V. Ley at Cambridge University (UK). His research is focussed on the development of an inductively heated micro flow system for organic synthesis.A key aspect of his work is the implementation of a multistep reaction and an immobilised catalyst into micro flow systems. Sascha Ceylan (right) was born in Augsburg, Germany, in 1981 and studied chemistry at Leibniz University Hannover and at Imperial College London under the guidance of Prof. A. G. M. Barrett (UK). He received his diploma degree in 2007 and thereafter began his doctoral studies in Hannover under the supervision of Prof. A. Kirschning. Following a research stay at the University of Hong Kong (Prof. P. Toy) he received his PhD early 2011. His scientific interest focuses on developing micro flow systems, especially inductively heated reactors, and investigations on palladium catalysed Umpolung reactions. Andreas Kirschning studied chemistry at the University of Hamburg and Southampton University (UK). In Hamburg, he joined the group of Prof. E. Schaumann and received his PhD in 1989 working in the field of organosilicon chemistry. After a postdoctoral stay at the University of Washington (Seattle, USA) with Prof. H. G. Floss, supported by a Feodor-Lynen scholarship of the Alexander-von Humboldt foundation, he started his independent research at the Clausthal University of Technology in 1991, where he finished his habilitation in 1996. In 2000 he moved to the Leibniz University Hannover and became a director of the institute of organic chemistry. He is one of the editors of RO ¨MPP online, Natural Products Reports and The Beilstein Journal of Organic Chemistry. His research interests cover structure elucidation as well as the total synthesis and mutasynthesis of natural products, biomedical biopolymers, and synthetic technology (solid-phase assisted synthesis, microreactors, inductive heating).

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“…31 Under flow conditions the rearrangement to the isocyanate was initiated which was trapped with different nucleophiles such as ethanol to yield carbamates like 32 (Scheme 8).…”

Section: This Journal Is C the Royal Society Of Chemistry 2011mentioning

confidence: 99%

Ten key issues in modern flow chemistry

2011

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“…For this reason, synthesis of the described acyl azides 3 and 6 started with readily available hydrazides in aq. HCl and NaNO 2 [7] rather than from non-basic precursors [8].…”

Section: Introductionmentioning

confidence: 99%

Acyl Azide Synthesis and Curtius Rearrangements in Microstructured Flow Chemistry Systems

Sprecher¹,

Payán²,

Weber³

et al. 2012

J Flow Chem

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The synthesis and utilisation of acyl azides in a flow apparatus combined with an automated extraction unit is described. This process safely provides multi-100 g quantities of a labile diacyl azide (3) as an intermediate that could not be generated safely by classic batch methods. Its subsequent conversion to the desired amine (4) represents an example for process intensification. The same set-up with an output capacity of >30 g/h was used for the unattended synthesis of benzoyl azide as the final product in solution (tert-butyl methyl ether (TBME), 0.5 M).

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“…Although there have been several reports on the Curtius rearrangement using flow systems, [7][8][9] none use TMSN 3 as an azide source. First, we optimized the Curtius rearrangement of TMSN 3 as an azide source employing the reaction of benzoyl chloride with TMSN 3 as a model reaction.…”

Section: Curtius Rearrangement In a Microreactormentioning

confidence: 96%

“…It was also found that the amount of reagent used was important. An excess of TMSN 3 reacted further with the generated phenyl isocyanate to form phenylcarbamoyl azide (9), and a given amount of TMSN 3 was required to suppress this side reaction. By using the optimized conditions, the desired product was obtained in good yield (92 %, Scheme 2).…”

Section: Curtius Rearrangement In a Microreactormentioning

confidence: 99%

“…[8] The same group also developed the Curtius rearrangement in a flow system using acyl chloride and azide monoliths. [9] In these methods, the sodium azide, DPPA, and azide monoliths were employed as azide sources. Trimethylsilyl azide (TMSN 3 ) is an alternative azide source that is safe and inexpensive, and the byproduct, TMSCl, can be easily removed.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of (–)‐Oseltamivir by Using a Microreactor in the Curtius Rearrangement

2011

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Azide monoliths as convenient flow reactors for efficient Curtius rearrangement reactions

Abstract: The preparation and use of an azide-containing monolithic reactor is described for use in a flow chemistry device and in particular for conducting Curtius rearrangement reactions via acid chloride inputs.

Cited by 117 publications

References 60 publications

Ten key issues in modern flow chemistry

Ten key issues in modern flow chemistry

Acyl Azide Synthesis and Curtius Rearrangements in Microstructured Flow Chemistry Systems

Synthesis of (–)‐Oseltamivir by Using a Microreactor in the Curtius Rearrangement

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