Visible‐Light/Photoredox‐Mediated sp<sup>3</sup> CH Functionalization and Coupling of Secondary Amines with Vinyl Azides in Flow Microreactors

Tiwari, Dharmendra Kumar; Maurya, Ram Awatar; Nanubolu, Jagadeesh Babu

doi:10.1002/chem.201504292

Cited by 58 publications

(21 citation statements)

References 85 publications

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“…Mechanistically, the secondary amine is oxidized to an imine, via the formation of a radical cation on the nitrogen atom. On the other hand, the vinyl azide is converted to a 2 H ‐azirine via photosensitization, followed by a series of ring opening and cyclization reactions, with the final rearrangement leading to the oxidation to imidazole …”

Section: Heterocyclic Synthesismentioning

confidence: 99%

Flow Chemistry: Towards A More Sustainable Heterocyclic Synthesis

2019

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Flow Chemistry is a revolutionary field in Organic Chemistry. By changing the conventional methods and apparatus applied in the chemical synthesis, flow chemistry emerges as a game changer for organic synthesis laboratories, in both academia and industries. Considered as a sustainable practice, flow processes play an important role in the development of fine chemical products and in drug discovery development pro- [a] The main advantages of flow chemistry are that it allows the reaction to be carried out safely with high selectivity, high reproducibility and reduced energy consumption/carbon footprint. These features make this emerging technology for organic synthesis desirable for green and sustainable chemical synthesis, giving the chemist time for work planning and design, instead of using it in repetitive tasks, [5b,12] as expressed by the CHEM21 project by awarding a green flag for continuousflow reactions, in opposition to an amber flag for those performed under batch conditions. [13] Pedro Brandão received his MSc in Pharmaceutical Sciences from the Faculty of Pharmacy -University of Porto, in 2011. Pursuing his passion on studies in the field of Drug Discovery and Development, he is currently undergoing his PhD studies in Chemistry, in the field of Catalysis and Sustainability. His main focus of work is the discovery of new drug candidates through sustainable techniques. Marta Pineiro received her Ph.D. in Organic Chemistry in 2003 in the University of Coimbra, Portugal, and since 2002 has been enrolled at the University of Coimbra, being at present Auxiliary Professor. Her research interests are in the area of sustainable organic synthesis, microwave-assisted organic synthesis and synthesis and biological applications of tetrapyrrolic macrocycles. Teresa M. V. D. Pinho e Melo studied Chemistry at the University of Coimbra, where she graduated in 1985, got her M. 7191CPBA) as the oxidizing agent, avoiding the handling of this expensive and explosive reagent. [25] Recently, Morodo et al. explored the synthesis of two very important oxiranes (epichlorohydrin and glycidol) from biobased glycerol, under flow conditions. As depicted in Scheme 1, and using pimelic acid as the catalyst (10 mol-%), a sequential hydrochlorination/dichlorination process allows high conversion of glycerol (> 99 %) into 1,3-dichloro-2-propanol, followed by the quantitative conversion into a separable mixture of glycidol and epichlorohydrin (2:3). The separation of these two products is performed by an in-line membrane separation system, which allows the first product to be collected in the aqueous phase, while the second is collected in MTBE. This heterocycle can be further used as a synthetic precursor to relevant APIs bearing -amino alcohol moieties (e.g., propranolol, alprenolol and naftopidil). [26] Scheme 1. Sequential flow setup for the preparation of glycidol and epichlorohydrin, important APIs synthetic intermediates.Scheme 3. Synthesis and inline purification of a bicyclic aziridine (SGMR = silicon-glass microfluidic react...

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Section: Heterocyclic Synthesismentioning

confidence: 99%

Flow Chemistry: Towards A More Sustainable Heterocyclic Synthesis

2019

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“…In contrast to large number of examples on photocatalytic SET oxidation‐mediated activation of tertiary amines, relatively little attention, however, has been devoted to the activation of secondary amines, although the visible light photoredox catalysis of such compounds would provide a practical access to neutral imines . Recently, Tiwari, Maurya and Nanubolu achieved a visible‐light‐induced photocatalytic cascade reaction between secondary amines such as tetrahydroisoquinoline 51 and α‐keto vinyl azides 52 under flow conditions at room temperature for the synthesis of structurally diverse imidazole derivatives 53 using tert ‐butyl hydroperoxide (TBHP) as an oxidant (Scheme ) . In analogy to the works of Yoon et al .…”

Section: Photocascade Catalysis Involving Energy Transfer and Singlementioning

confidence: 99%

Photocascade Catalysis: A New Strategy for Cascade Reactions

et al. 2017

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This Concept article highlights recent advances in the rapidly developing field of visible‐light‐driven, single‐photocatalyst‐promoted photocascade catalysis and its application in the discovery of novel reactivities suitable for cascade reactions. Examples of photocascade catalytic transformations are categorized by the activation modes of substrates and intermediates involved in these processes. It is hoped that this emerging catalysis strategy will enable chemists to develop many more useful, sustainable and sophisticated cascade synthetic transformations in the near future.

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“…This method has been extended to indole synthesis. Recently, imidazole derivatives were prepared by photoredox‐catalyzed coupling of vinyl azides and secondary amines in flow microreactors …”

Section: Synthesis Of Heteroarenesmentioning

confidence: 99%

Construction and Functionalization of Heteroarenes by Use of Photoredox Catalysis

Boubertakh

Goddard

2017

Eur J Org Chem

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Visible‐Light/Photoredox‐Mediated sp³ CH Functionalization and Coupling of Secondary Amines with Vinyl Azides in Flow Microreactors

Cited by 58 publications

References 85 publications

Flow Chemistry: Towards A More Sustainable Heterocyclic Synthesis

Flow Chemistry: Towards A More Sustainable Heterocyclic Synthesis

Photocascade Catalysis: A New Strategy for Cascade Reactions

Construction and Functionalization of Heteroarenes by Use of Photoredox Catalysis

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Visible‐Light/Photoredox‐Mediated sp3 CH Functionalization and Coupling of Secondary Amines with Vinyl Azides in Flow Microreactors

Cited by 58 publications

References 85 publications

Flow Chemistry: Towards A More Sustainable Heterocyclic Synthesis

Flow Chemistry: Towards A More Sustainable Heterocyclic Synthesis

Photocascade Catalysis: A New Strategy for Cascade Reactions

Construction and Functionalization of Heteroarenes by Use of Photoredox Catalysis

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Visible‐Light/Photoredox‐Mediated sp³ CH Functionalization and Coupling of Secondary Amines with Vinyl Azides in Flow Microreactors