Mn-mediated reductive C(sp3)–Si coupling of activated secondary alkyl bromides with chlorosilanes

Qi, Liangliang; Pang, Xiaoyang; Yin, Kai; Pan, Qiu-Quan; Wei, Xiao‐Xue; Shu, Xing‐Zhong

doi:10.1016/j.cclet.2022.03.070

Cited by 19 publications

(3 citation statements)

References 68 publications

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“…At present, there are only a few special substrates (e.g., α-bromo organophosphorus and sulfones) that have shown the ability to react with common chlorosilanes (Scheme ). The reaction was promoted by Mn, but the addition of NiI 2 (5 mol %) increased the yield of the coupling product in some cases. Mechanistically, a transition-metal catalytic cycle may not be involved, and the nucleophilic substitution of enol intermediate to chlorosilanes was suggested as a key step for this process.…”

Section: Reductive Coupling Of Chlorosilanesmentioning

confidence: 99%

Reductive Cross-Coupling of Unreactive Electrophiles

2022

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Metrics & MoreArticle Recommendations CONSPECTUS: Transition-metal-catalyzed reductive coupling of electrophiles has emerged as a powerful tool for the construction of molecules. While major achievements have been made in the field of cross-couplings between organic halides and pseudohalides, an increasing number of reports demonstrates reactions involving more readily available, low-cost, and stable, but unreactive electrophiles. This account summarizes the recent results in our laboratory focusing on this topic. These findings typically include deoxygenative C−C coupling of alcohols, reductive alkylation of alkenyl acetates, reductive C−Si coupling of chlorosilanes, and reductive C−Ge coupling of chlorogermanes.The reductive deoxygenative coupling of alcohols with electrophiles is synthetically appealing, but the potential of this chemistry remains to be disclosed. Our initial study focused on the reaction of allylic alcohols and aryl bromides by the combination of nickel and Lewis acid catalysis. This method offers a selectivity that is opposite to that of the classic Tsuji−Trost reactions. Further investigation on the reaction of benzylic alcohols led to the foundation of a dynamic kinetic cross-coupling strategy with applications in the nickelcatalyzed reductive arylation of benzylic alcohols and cobalt-catalyzed enantiospecific reductive alkenylation of allylic alcohols. The titanium catalysis was later established to produce carbon radicals directly from unactivated tertiary alcohols via C−OH cleavage.The development of their coupling reactions with carbon fragments delivers new methods for the construction of all-carbon quaternary centers. These reactions have shown high selectivity for the functionalization of tertiary alcohols, leaving primary and secondary alcohols intact. Alkenyl acetates are inexpensive, stable, and environmentally friendly and are considered the most attractive alkenyl reagents. The development of reductive alkylation of alkenyl acetates with benzyl ammoniums and alkyl bromides offers mild approaches for the conversion of ketones into aliphatic alkenes. Extensive studies in this field have enabled us to extend the cross-electrophile coupling from carbon to silicon and germanium chemistry. These reactions harness the ready availability of chlorosilanes and chlorogermanes but suffer from the challenge of their low reactivity toward transition metals. Under reductive nickel catalysis, a broad range of alkenyl and aryl electrophiles couple well with vinyl-and hydrochlorosilanes. The use of alkyl halides as coupling partners led to the formation of functionalized alkylsilanes. The C−Ge coupling seems less substrate-dependent, and various common chlorogermanes couple well with aryl, alkenyl, and alkyl electrophiles. In general, functionalities such as Grignard-sensitive groups (e.g., acid, amide, alcohol, ketone, and ester), acid-sensitive groups (e.g., ketal and THP protection), alkyl fluoride and chloride, aryl bromide, alkyl tosylate and mesylate, silyl ether, and amine are tolerated. ...

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Section: Reductive Coupling Of Chlorosilanesmentioning

confidence: 99%

Reductive Cross-Coupling of Unreactive Electrophiles

2022

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“…of heteroatoms, the substituents containing heteroatoms could change the properties and reaction characteristics of the molecules, especially in adjacent positions. 9 c ,10 In addition, the coordination of π-acidic CO and heteroatoms with metal catalysts might decrease or even inhibit metal catalytic activity. 11 On the other hand, the rate of decarbonylation depends strongly on the nature of substituents, and the α-heteroatoms can effectively stabilize the adjacent carbon radicals, resulting in acyl radicals that tend to decarbonylate to form a stable radical species, especially at lower CO pressures or higher temperatures.…”

Section: Introductionmentioning

confidence: 99%

Nickel/photoredox-catalyzed carbonylative transformations of α-phosphorus-, α-sulfur-, and α-boron-substituted alkyl halides

Wang,

2024

Org. Chem. Front.

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“…According to statistics, the global demand for 2,4-dichloro-5-fluoroacetophenone is about 7000 tons, while the domestic demand for 2,4-dichloro-5-fluoroacetophenone in China is about 4000 tons. At present, o -dichlorobenzene is widely used as a raw material in industry to produce 2,4-dichloro-5-fluoroacetophenone through nitration, fluorination, nitrochlorination, and acetylation reactions. − Although these four reactions are classical, there are still some shortcomings that need improvement in the actual production. The first reaction is to react nitrate o -dichlorobenzene with mixed acid, which will generate a large amount of waste acid and cause serious environmental pollution.…”

Section: Introductionmentioning

confidence: 99%

Development of an Optimized Process for 2,4-Dichloro-5-fluoroacetophenone: A Key Intermediate of Ciprofloxacin

Yin,

He,

et al. 2024

Org. Process Res. Dev.

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Herein, we report an optimized process for 2,4-dichloro-5-fluoroacetophenone, a key intermediate of ciprofloxacin. In the nitration step, the traditional mixed acid process was replaced by a microchannel continuous reaction technology. For the fluorination reactions, the traditional quaternary ammonium salt catalyst was replaced by a novel CNC + catalyst, which led to improved catalytic efficiency, lowered reaction temperatures, and increased product yields. Furthermore, a cost-effective method for utilizing waste gases with high concentrations of nitrogen oxides was developed for the nitrochlorination reaction. In the acetylation step, magnetic materials featuring both Bronsted and Lewis acid sites were utilized to immobilize the bisacid site catalyst [HPhIm][FeCl 4 ]/MPNs, replacing the traditional AlCl 3 approach. The overall yield of this new sustainable process across all four steps reached 86.4%, marking a significant improvement of over 10% compared to the traditional method. Moreover, the new process has resulted in an 87% reduction in waste acid emissions and a remarkable 96% reduction in exhaust emissions.

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Mn-mediated reductive C(sp3)–Si coupling of activated secondary alkyl bromides with chlorosilanes

Cited by 19 publications

References 68 publications

Reductive Cross-Coupling of Unreactive Electrophiles

Reductive Cross-Coupling of Unreactive Electrophiles

Nickel/photoredox-catalyzed carbonylative transformations of α-phosphorus-, α-sulfur-, and α-boron-substituted alkyl halides

Development of an Optimized Process for 2,4-Dichloro-5-fluoroacetophenone: A Key Intermediate of Ciprofloxacin

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