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1. Remote C–H Functionalization via Selective Hydrogen Atom Transfer

   https://doi.org/10.1055/s-0036-1591930  

   Stateman, Leah; Nakafuku, Kohki; Nagib, David (April 2018, Synthesis)

   The selective functionalization of remote C–H bonds via intramolecular hydrogen atom transfer (HAT) is transformative for organic synthesis. This radical-mediated strategy provides access to novel reactivity that is complementary to closed-shell pathways. As modern methods for mild generation of radicals are continually developed, inherent selectivity paradigms of HAT mechanisms offer unparalleled opportunities for developing new strategies for C–H functionalization. This review outlines the history, recent advances, and mechanistic underpinnings of intramolecular HAT as a guide to addressing ongoing challenges in this arena. 1 Introduction 2 Nitrogen-Centered Radicals 2.1 sp3 N-Radical Initiation 2.2 sp2 N-Radical Initiation 3 Oxygen-Centered Radicals 3.1 Carbonyl Diradical Initiation 3.2 Alkoxy Radical Initiation 3.3 Non-alkoxy Radical Initiation 4 Carbon-Centered Radicals 4.1 sp2 C-Radical Initiation 4.2 sp3 C-Radical Initiation 5 Conclusion 

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2. Nitrene transfer catalysts for enantioselective C–N bond formation

   https://doi.org/10.1038/s41570-021-00291-4  

   Ju, Minsoo; Schomaker, Jennifer M. (August 2021, Nature Reviews Chemistry)
3. C∙∙∙O and Si∙∙∙O Tetrel Bonds: Substituent Effects and Transfer of the SiF3 Group

   https://doi.org/10.3390/ijms241511884  

   Niu, Zhihao; Wu, Qiaozhuo; Li, Qingzhong; Scheiner, Steve (August 2023, International Journal of Molecular Sciences)

   The tetrel bond (TB) between 1,2-benzisothiazol-3-one-2-TF3-1,1-dioxide (T = C, Si) and the O atom of pyridine-1-oxide (PO) and its derivatives (PO-X, X = H, NO2, CN, F, CH3, OH, OCH3, NH2, and Li) is examined by quantum chemical means. The Si∙∙∙O TB is quite strong, with interaction energies approaching a maximum of nearly 70 kcal/mol, while the C∙∙∙O TB is an order of magnitude weaker, with interaction energies between 2.0 and 2.6 kcal/mol. An electron-withdrawing substituent on the Lewis base weakens this TB, while an electron-donating group has the opposite effect. The SiF3 group transfers roughly halfway between the N of the acid and the O of the base without the aid of cooperative effects from a third entity. 

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4. Bidirectional C and N transfer and a potential role for sulfur in an epiphytic diazotrophic mutualism

   https://doi.org/10.1038/s41396-020-00738-4  

   Stuart, Rhona K.; Pederson, Eric R.; Weyman, Philip D.; Weber, Peter K.; Rassmussen, Ulla; Dupont, Christopher L. (August 2020, The ISME Journal)

   In nitrogen-limited boreal forests, associations between feathermoss and diazotrophic cyanobacteria control nitrogen inputs and thus carbon cycling, but little is known about the molecular regulators required for initiation and maintenance of these associations. Specifically, a benefit to the cyanobacteria is not known, challenging whether the association is a nutritional mutualism. Targeted mutagenesis of the cyanobacterial alkane sulfonate monooxygenase results in an inability to colonize feathermosses by the cyanobacterium Nostoc punctiforme, suggesting a role for organic sulfur in communication or nutrition. Isotope probing paired with high-resolution imaging mass spectrometry (NanoSIMS) demonstrated bidirectional elemental transfer between partners, with carbon and sulfur both being transferred to the cyanobacteria, and nitrogen transferred to the moss. These results support the hypothesis that moss and cyanobacteria enter a mutualistic exosymbiosis with substantial bidirectional material exchange of carbon and nitrogen and potential signaling through sulfur compounds. 

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5. Isolable iodosylarene and iodoxyarene adducts of Co and their O-atom transfer and C–H activation reactivity

   https://doi.org/10.1039/C8SC01167B  

   Hill, Ethan A.; Kelty, Margaret L.; Filatov, Alexander S.; Anderson, John S. (January 2018, Chemical Science)

   We report an unusual series of discrete iodosyl- and iodoxyarene adducts of Co. The formation of these adducts was confirmed by a suite of techniques including single crystal X-ray diffraction. The reactivity of these adducts with O-atom acceptors and an H-atom donor has been investigated with particular focus on elucidating mechanistic details. Detailed kinetic analysis allows for discrimination between proposed oxo and adduct mediated mechanisms. In particular, these reactions have been interrogated by competition experiments with isotopically labelled mixtures which shows that all of the studied adducts display a large KIE. These studies suggest different mechanisms may be relevant depending on subtle substituent changes in the adduct complexes. Reactivity data are consistent with the involvement of a transient oxo complex in one case, while the two other systems appear to react with substrates directly as iodosyl- or iodoxyarene adducts. These results support that reactivity typically ascribed to metal-oxo complexes, such as O-atom transfer and C–H activation, can also be mediated by discrete transition metal iodosyl- or iodoxyarene adducts that are frequent intermediates in the generation of oxo complexes. The influence of additional Lewis acids such as Sc 3+ on the reactivity of these systems has also been investigated. 

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