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1. Photochemistry of N ‐aryl and N ‐alkyl dibenzothiophene sulfoximines

   https://doi.org/10.1111/php.13978  

   Throgmorton, John C; Iverson, Alexis J; McCulla, Ryan D (June 2024, Photochemistry and Photobiology)

   Abstract N‐phenyl dibenzothiophene sulfoximine has been demonstrated to produce phenyl nitrene and dibenzothiopheneS‐oxide upon irradiation with UV‐A light, and dibenzothiopheneS‐oxide upon further irradiation releases triplet atomic oxygen. Thus,N‐phenyl dibenzothiophene sulfoximine exhibits a rare dual‐release capability in its photochemistry. In this work,N‐substituted dibenzothiophene sulfoximine derivatives are irradiated with UV‐A light to compare their photochemistry and quantum yield of dibenzothiopheneS‐oxide production with that ofN‐phenyl dibenzothiophene sulfoximine. BothN‐aryl andN‐alkyl derivatives of dibenzothiophene sulfoximine are examined to observe their effects on the quantum yield of the photolysis reaction. Adding electron withdrawingN‐aryl substituents is shown to increase the quantum yield of dibenzothiopheneS‐oxide production, while adding electron donatingN‐aryl substituents is shown to decrease the quantum yield. The quantum yield was slightly lowered or not increased by mostN‐alkyl substituents. Furthermore, the quantum yield was not augmented by branching and steric hindrance effects associated with theN‐alkyl substituents. These results suggest that electronic modulation of the sulfoximine bonds affects the observed photolysis reaction. 

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2. N , N -Diethylurea-Catalyzed Amidation between Electron-Deficient Aryl Azides and Phenylacetaldehydes

   https://doi.org/10.1021/ol503655a  

   Xie, Sheng; Ramström, Olof; Yan, Mingdi (February 2015, Organic Letters)
3. N -Vinyl and N -Aryl Hydroxypyridinium Ions: Charge-Activated Catalysts with Electron-Withdrawing Groups

   https://doi.org/10.1021/acs.joc.0c00498  

   Riegel, George F.; Kass, Steven R. (May 2020, The Journal of Organic Chemistry)
4. Chemoselective acylation of N -acylglutarimides with N -acylpyrroles and aryl esters under transition-metal-free conditions

   https://doi.org/10.1039/D1QO00992C  

   Li, Jie; Yao, Jiaqi; Chen, Lingfeng; Zou, Dong; Walsh, Patrick J.; Liang, Guang (November 2021, Organic Chemistry Frontiers)

   The imide moiety is a well-known structural motif in bioactive compounds and a useful building block in a variety of processes. Using N -acylglutarimides with MN(SiMe 3 ) 2 and either N -acylpyrroles or aryl esters, an operationally convenient method to produce a wide array of diaryl- and alkyl arylimides is presented. Symmetric imides are also accessible when N -acylglutarimides are employed as acylation reagents under similar reaction conditions. A unique feature of this method stems from the use of two different electrophilic acylating reagents leading to the formation of the unsymmetrical imides with excellent chemoselectivity. 

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5. Effects of the Chalcogenide Identity in N ‐Aryl Phenochalcogenazine Photoredox Catalysts

   https://doi.org/10.1002/cctc.202200485  

   Corbin, Daniel_A; Cremer, Christopher; Puffer, Katherine_O; Newell, Brian_S; Patureau, Frederic_W; Miyake, Garret_M (July 2022, ChemCatChem)

   Abstract Phenochalcogenazines such as phenoxazines and phenothiazines have been widely employed as photoredox catalysts (PCs) in small molecule and polymer synthesis. However, the effect of the chalcogenide in these catalysts has not been fully investigated. In this work, a series of four phenochalcogenazines is synthesized to understand how the chalcogenide impacts catalyst properties and performance. Increasing the size of the chalcogenide is found to distort the PC structure, ultimately impacting the properties of each PC. For example, larger chalcogenides destabilize the PC radical cation, possibly resulting in catalyst degradation. In addition, PCs with larger chalcogenides experience increased reorganization during electron transfer, leading to slower electron transfer. Ultimately, catalyst performance is evaluated in organocatalyzed atom transfer radical polymerization and a photooxidation reaction for C(sp²)−N coupling. Results from these experiments highlight that a balance of PC properties is most beneficial for catalysis, including a long‐lived excited state, a stable radical cation, and a low reorganization energy. 

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