Discovery of a photochemical cascade process by flow-based interception of isomerising alkenes

Filippo, Mara Di; Trujillo, Cristina; Sánchez‐Sanz, Goar; Batsanov, Andrei S.; Baumann, Marcus

doi:10.1039/d1sc02879k

Cited by 17 publications

(11 citation statements)

References 39 publications

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“…Moving from cinchonine 4 to its phenyl carbamate 9 derivative spectacularly improved both conversion and reactions yields since compounds 16 and 22 – 26 reached >98 % conversion after only 2.5 minutes of residence time and isolated yields ranged from 86 to 95 %. We attribute the exceptional reactivity of cinchona alkaloid derivatives 7 and 9 for thiol‐ene reactions – much higher than those usually observed in batch processes – to the conjunction of beneficial factors: i/the high photon flux allowed in the flow photochemical reactor, [17–19] ii/the high reproducibility of photochemical reactions in flow [20–27] and iii/the control of a highly reactive conformation in solution.…”

Section: Resultsmentioning

confidence: 96%

Ultra‐Fast Continuous‐Flow Photo‐Thiol‐Ene Functionalization of Conformation‐Controlled Cinchona Alkaloids

2022

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In this work, we describe ultra-fast continuous flow photo-thiolene reactions on cinchona alkaloids derivatives through a control of the reactive conformation in solution. Flow thiol-ene reactions proceed at 32 °C under light irradiation at 365 nm and require only 2.5 minutes of residence time to reach completion. The short path length of the tubular flow photochemical reactor, which maximizes and homogenizes the photon flux, associated to the fine tuning of the reactive conformation of cinchona alkaloids in solution are the main reasons for the high rates observed. The predominant conformation in solution of cinchona alkaloids was adjusted through the substitution of the hydroxyl group at C9 by a phenyl carbamate function.

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Section: Resultsmentioning

confidence: 96%

Ultra‐Fast Continuous‐Flow Photo‐Thiol‐Ene Functionalization of Conformation‐Controlled Cinchona Alkaloids

2022

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“…To gain insight into this interplay, geometry optimizations using density functional theory (DFT) have been carried out for compounds 7a – d , 11a–b , 15c , and 17 . To do this, three functionals CAM-B3LYP, WB97XD, and M06-2X were used with def2TZVP as the basis set. − Frequency calculations have been carried out to verify the nature of the minima, and for each compound, true minima have been identified with no imaginary frequencies. According to these calculations, the CAM-B3LYP results most closely match the experimental outcomes (additional data obtained using the other functionals can be found in the Supporting Information).…”

Section: Resultsmentioning

confidence: 99%

Reduction of Substituted Benzo-Fused Cyclic Sulfonamides with Mg-MeOH: An Experimental and Computational Study

et al. 2022

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A study involving the use of Mg-MeOH for the double reductive cleavage of both N–S and C–S bonds in a series of 11 benzo-fused cyclic sulfonamides is reported. Examples where the sulfonamide nitrogen atom is part of a pyrrolidine ring effectively undergo reduction, as long as a methoxy substituent is not para -positioned in the aromatic ring, relative to the sulfonyl group. In contrast, if the nitrogen atom is contained within an aromatic ring (pyrrole or indole), the presence of a para -methoxy substituent does not prohibit reduction. If deuterated methanol is used, aromatic ortho- deuterium incorporation was observed. To better understand how structure affects reactivity, density functional theory calculations were performed using three functionals. Results using CAM-B3LYP were found to best correlate with experimental observations, and these demonstrate the impact that the different aromatic substitution patterns and types of N-atom have on the lowest unoccupied molecular orbital (LUMO) energies and adiabatic electron affinities.

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“…In addition to being used as stoichiometric reagent, carbenes can act as key intermediates during intramolecular reactions, as observed by the Baumann group in the photochemical cyclization of chalcones. 55 Building on previous work investigating the intramolecular cyclization of chalcones to synthesize quinolines, 56 a recent study utilized chalcones bearing an alkyne group. Irradiation of the alkyne bearing chalcone 24 led to the complex polycyclic product 26a .…”

Section: Use Of Carbenes In Continuous Flowmentioning

confidence: 99%

Continuous Flow Technology as an Enabler for Innovative Transformations Exploiting Carbenes, Nitrenes, and Benzynes

Donnelly

Baumann

2022

J. Org. Chem.

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Miniaturization offered by microreactors provides for superb reaction control as well as excellent heat and mass transfer. By performing chemical reactions in microreactors or tubular systems under continuous flow conditions, increased safety can be harnessed which allows exploitation of these technologies for the generation and immediate consumption of high-energy intermediates. This Synopsis demonstrates the use of flow technology to effectively exploit benzynes, carbenes, and nitrenes in synthetic chemistry programs.

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Discovery of a photochemical cascade process by flow-based interception of isomerising alkenes

Abstract: Herein we report the discovery of a new photochemical cascade process through a flow-based strategy for intercepting diradicals generated from simple alkenes. This continuous process delivers a series of unprecedented...

Cited by 17 publications

References 39 publications

Ultra‐Fast Continuous‐Flow Photo‐Thiol‐Ene Functionalization of Conformation‐Controlled Cinchona Alkaloids

Ultra‐Fast Continuous‐Flow Photo‐Thiol‐Ene Functionalization of Conformation‐Controlled Cinchona Alkaloids

Reduction of Substituted Benzo-Fused Cyclic Sulfonamides with Mg-MeOH: An Experimental and Computational Study

Continuous Flow Technology as an Enabler for Innovative Transformations Exploiting Carbenes, Nitrenes, and Benzynes

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