Exploiting Imine Photochemistry for Masked N‐Centered Radical Reactivity

Staveness, Daryl; Collins, James L.; McAtee, Rory C.; Stephenson, Corey R. J.

doi:10.1002/anie.201909492

Cited by 53 publications

(33 citation statements)

References 71 publications

(97 reference statements)

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“…Therefore, to circumvent this possibility, we considered an unconventional strategy of exciting the C=N bond to a biradical state A , which we proposed would readily undergo β-scission ( Figure 1 B). 24 Currently, the photolysis of N -alkylimines 25 requires direct UV irradiation. However, we were inspired by related oxime chemistry, 26 in which recent breakthroughs have used accessible visible-light triplet energy-transfer (EnT) catalysis to achieve oxime fragmentation 27 and cyclization.…”

Section: Resultsmentioning

confidence: 99%

Photocatalytic Late-Stage Functionalization of Sulfonamides via Sulfonyl Radical Intermediates

et al. 2022

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A plethora of drug molecules and agrochemicals contain the sulfonamide functional group. However, sulfonamides are seldom viewed as synthetically useful functional groups. To confront this limitation, a late-stage functionalization strategy is described, which allows sulfonamides to be converted to pivotal sulfonyl radical intermediates. This methodology exploits a metal-free photocatalytic approach to access radical chemistry, which is harnessed by combining pharmaceutically relevant sulfonamides with an assortment of alkene fragments. Additionally, the sulfinate anion can be readily obtained, further broadening the options for sulfonamide functionalization. Mechanistic studies suggest that energy-transfer catalysis (EnT) is in operation.

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Section: Resultsmentioning

confidence: 99%

Photocatalytic Late-Stage Functionalization of Sulfonamides via Sulfonyl Radical Intermediates

et al. 2022

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“…Our laboratory recently disclosed a formal strain-driven intramolecular [3+2] cycloaddition for the synthesis of 1-aminonorbornanes (1-aminoNBs)( Figure 1B). 14 This methodology exploited visible-light imine photochemistry to generate an excited state diyl, which in turn initiated strain-driven fragmentation of a cyclopropane ring and serial cyclization reactions to generate the final 1-aminoNB product.…”

Section: Introductionmentioning

confidence: 99%

A One Pot Photochemical Method for the Generation of Functionalized Aminocyclopentanes

Sowden¹,

Collins²,

Staveness³

et al. 2020

Preprint

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<div>Detailed herein is the development of a photochemical intermolecular formal [3+2] cycloaddition between cyclopropylimines and substituted alkenes to generate cyclopentylimines. The Schiff base auxiliary of the cyclopropylimine was designed to enable a masked N-centered radical approach in which the requisite open-shell character was achieved upon excitation with violet light. The cycloaddition products were directly converted to N-functionalized aminocyclopentanes via N-acylation and solvolysis, thus offering a three-step, one-pot procedure for the production of diversely-substituted aminocyclopentanes. The photochemical component of this reaction sequence was demonstrated to operate in continuous flow and was amenable to gram-scale production.</div>

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“…Therefore, micro uidic systems with large surface-area-to-volume ratios are promising platforms to overcome such restrictions toward e cient photocatalytic organic synthesis. [4][5][6][7][8] This approach affords various advantages, such as short light pathway and uniform distribution of light, which lead to a noticeable decrease in reaction time and increase in the product yield or selectivity compared to those obtained using batch reactors, even under mild conditions. [9][10][11][12] Recently, several micro uidic systems e ciently harvest light by exploiting the Stokes-shift phenomenon.…”

Section: Introductionmentioning

confidence: 99%

Dual-modal Light-harvesting Microfluidic System via Simultaneous Up- and Down-Conversions for Enhanced Flow Photocatalysis

Kim

You

Ahn

et al. 2020

Preprint

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Microfluidic systems with large surface-to-volume ratios enable photocatalytic reactions to occur, avoiding the limitations of light penetration and allow the efficient transfer/mixing of mass and energy. For enhanced photocatalysis, the utilization of broad-spectrum light, especially over the entire solar spectrum, is highly desirable, but has been less explored in microfluidic systems. Herein, we report a novel microfluidic system with dual-modal light-harvesting capability via simultaneous up- and down-conversions to significantly improve the photocatalytic efficiency of C(sp3)-H functionalization reactions using ultraviolet (UV) to near-infrared (NIR) light. A transparent composite incorporating down-converting (DC) coumarin dye and up-converting (UC) lanthanide-doped nanocrystals (β-NaYF4:Yb/Er/Gd) was coated onto the inner surface of the microchannels, which showed effective dual conversion of UV/NIR to visible light. An improved photocatalytic organic transformation using our single- or double-stacked microfluidic system was achieved utilizing a photocatalytic aza-Henry reaction with rose bengal (RB), which displayed a two-fold increase in reaction conversion.

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Exploiting Imine Photochemistry for Masked N‐Centered Radical Reactivity

Cited by 53 publications

References 71 publications

Photocatalytic Late-Stage Functionalization of Sulfonamides via Sulfonyl Radical Intermediates

Photocatalytic Late-Stage Functionalization of Sulfonamides via Sulfonyl Radical Intermediates

A One Pot Photochemical Method for the Generation of Functionalized Aminocyclopentanes

Dual-modal Light-harvesting Microfluidic System via Simultaneous Up- and Down-Conversions for Enhanced Flow Photocatalysis

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