Redox-chain decomposition of hydroxylamine-O-sulphonic acid. A novel general source of nucleophilic radicals for the functionalization of heteroaromatic bases

Citterio, Attilio; Gentile, Anna; Minisci, Francesco; Serravalle, Marco; Ventura, Susanna

doi:10.1039/c39830000916

Cited by 28 publications

(7 citation statements)

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“…Surprisingly, the C(sp 3 )–H borylation reaction was observed to selectively occur at the distal methyl group, indicating that steric hindrance had a significant effect on the borylation reactivity, whereas borylation could not take place at the α-position of the carbonyl group in all of the cases. Due to the presence of the carbonyl group and alkene in the structure, the allylic position ( 5 ) and the terminal methyl group adjacent to oxygen ( 6 ) are deactivated for HAT reactivity, thus exclusively generating β-borylated products 5 and 6 in 32 and 52% yields, respectively . When there were two different distal β-methyl groups present in the substrate, the selectivity was decreased to some extent ( 10 ).…”

Section: Resultsmentioning

confidence: 99%

Iron-Catalyzed C(Sp³)–H Borylation, Thiolation, and Sulfinylation Enabled by Photoinduced Ligand-to-Metal Charge Transfer

Guo

et al. 2023

J. Am. Chem. Soc.

104

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Catalytic C(sp 3 )−H functionalization has provided enormous opportunities to construct organic molecules, facilitating the derivatization of complex pharmaceutical compounds. Within this framework, direct hydrogen atom transfer (HAT) photocatalysis becomes an appealing approach to this goal. However, the viable substrates utilized in these protocols are limited, and the site selectivity shows preference to activated and thermodynamically favored C(sp 3 )−H bonds. Herein, we describe the development of undirected iron-catalyzed C(sp 3 )−H borylation, thiolation, and sulfinylation reactions enabled by the photoinduced ligand-to-metal charge transfer (LMCT) process. These reactions exhibit remarkably broad substrate scope (>150 examples in total), and most importantly, all of these three reactions show unconventional regioselectivity, with the occurrence of C(sp 3 )−H borylation, thiolation, and sulfinylation preferentially at the distal methyl position. The procedures are operationally simple and readily scalable and provide access to high-value products from simple hydrocarbons in one step. Mechanistic studies and control experiments indicate that the afforded site selectivity is not only relevant to the HAT species but also largely affected by the use of boron-and sulfone-based radical acceptors.

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Section: Resultsmentioning

confidence: 99%

Iron-Catalyzed C(Sp³)–H Borylation, Thiolation, and Sulfinylation Enabled by Photoinduced Ligand-to-Metal Charge Transfer

Guo

et al. 2023

J. Am. Chem. Soc.

104

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“…As mentioned above, α-arylalkylamides can be obtained from alkylamides and arenes through oxidation of alkylamides followed by S E Ar with the resulting α-oxyalkylamides, but tandem reaction consisting of these two reactions is more convenient because introduction of oxy substituents in advance is not required. In this context, we have previously reported the Zr(OTf) 4 -catalyzed oxidative coupling of alkylamides with arenes using O 2 as an oxidant, but the scope is severely limited to γ-lactams and electron-rich heteroarenes. , This oxidative coupling is considered to be a tandem reaction consisting of oxidation and S E Ar both catalyzed by the zirconium complex, though the existence of any intermediary α-oxygenated alkylamide is not confirmed. It is not so easy to effectively operate this type of tandem catalysis, where one catalyst sequentially promotes two mechanistically distinct reactions in a single reactor, because the catalyst is required to show two different types of catalytic abilities.…”

Section: Introductionmentioning

confidence: 99%

Iron-Catalyzed Oxidative Coupling of Alkylamides with Arenes through Oxidation of Alkylamides Followed by Friedel−Crafts Alkylation

2010

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FeCl(3) in combination with t-BuOOt-Bu as an oxidant was found to be an efficient catalyst for oxidation of alkylamides to α-(tert-butoxy)alkylamides. FeCl(2) and CuCl showed, respectively, almost the same and slightly lower activities compared with FeCl(3) in the tert-butoxylation of N-phenylpyrrolidone (1a), whereas no tert-butoxylated product was obtained by use of Fe(OTf)(3), RuCl(3), or Zr(OTf)(4). FeCl(3) was found to be effective also as a catalyst for the Friedel-Crafts alkylation with thus obtained α-(tert-butoxy)alkylamides. The Friedel-Crafts alkylation proceeded smoothly also in the presence of a catalytic amount of Fe(OTf)(3), RuCl(3), or Zr(OTf)(4). In contrast, FeCl(2) and CuCl, which showed certain activity toward the tert-butoxylation, failed to promote the Friedel-Crafts alkylation. Among the transition metal complexes thus far examined, only FeCl(3) showed high catalytic activities for both the oxidation and the Friedel-Crafts alkylation. The bifunctionality of FeCl(3) was utilized for the oxidative coupling of alkylamides with arenes through a tandem reaction consisting of oxidation of alkylamides to α-(tert-butoxy)alkylamides and the following Friedel-Crafts alkylation. The FeCl(3)-catalyzed oxidative coupling is applicable to a wide variety of alkylamides and arenes, though a combination of FeCl(3) with Fe(OTf)(3) was found to be effective for the reaction of arenes with low nucleophilicity. A Fe(II)-Fe(III) catalytic cycle is concerned with the tert-butoxylation, whereas a Fe(III) complex as a Lewis acid catalyzes the Friedel-Crafts alkylation.

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“…Thus, 4-ethyl pyridine provided a mixture of 4ethyl-N,N-dimethylpicolinamide and N-((4-ethylpyridin-2-yl)methyl)-N-methylformamide in yields and ratios depending on the oxidant (Scheme 38a). This seminal report was followed by intensive studies on the radical fragmentation of DM by Minisci and co-workers [116][117][118]. Then, the promotion of such reactions under sunlight, especially in the presence of TiO2, was disclosed by Caronna and co-workers (Scheme 38b) [119].…”

Section: Rc=on(ch2)me Fragmentmentioning

confidence: 97%

A Journey from June 2018 to October 2021 with N,N-Dimethylformamide and N,N-Dimethylacetamide as Reactants

Мuzart¹

2021

Molecules

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Redox-chain decomposition of hydroxylamine-O-sulphonic acid. A novel general source of nucleophilic radicals for the functionalization of heteroaromatic bases

Cited by 28 publications

References 0 publications

Iron-Catalyzed C(Sp³)–H Borylation, Thiolation, and Sulfinylation Enabled by Photoinduced Ligand-to-Metal Charge Transfer

Iron-Catalyzed C(Sp³)–H Borylation, Thiolation, and Sulfinylation Enabled by Photoinduced Ligand-to-Metal Charge Transfer

Iron-Catalyzed Oxidative Coupling of Alkylamides with Arenes through Oxidation of Alkylamides Followed by Friedel−Crafts Alkylation

A Journey from June 2018 to October 2021 with N,N-Dimethylformamide and N,N-Dimethylacetamide as Reactants

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Redox-chain decomposition of hydroxylamine-O-sulphonic acid. A novel general source of nucleophilic radicals for the functionalization of heteroaromatic bases

Cited by 28 publications

References 0 publications

Iron-Catalyzed C(Sp3)–H Borylation, Thiolation, and Sulfinylation Enabled by Photoinduced Ligand-to-Metal Charge Transfer

Iron-Catalyzed C(Sp3)–H Borylation, Thiolation, and Sulfinylation Enabled by Photoinduced Ligand-to-Metal Charge Transfer

Iron-Catalyzed Oxidative Coupling of Alkylamides with Arenes through Oxidation of Alkylamides Followed by Friedel−Crafts Alkylation

A Journey from June 2018 to October 2021 with N,N-Dimethylformamide and N,N-Dimethylacetamide as Reactants

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Iron-Catalyzed C(Sp³)–H Borylation, Thiolation, and Sulfinylation Enabled by Photoinduced Ligand-to-Metal Charge Transfer

Iron-Catalyzed C(Sp³)–H Borylation, Thiolation, and Sulfinylation Enabled by Photoinduced Ligand-to-Metal Charge Transfer