3699-03-4Relevant academic research and scientific papers
Photoredox Nickel-Catalyzed C-S Cross-Coupling: Mechanism, Kinetics, and Generalization
Qin, Yangzhong,Sun, Rui,Gianoulis, Nikolas P.,Nocera, Daniel G.
supporting information, p. 2005 - 2015 (2021/02/06)
Photoredox-mediated nickel-catalyzed cross-couplings have evolved as a new effective strategy to forge carbon-heteroatom bonds that are difficult to access with traditional methods. Experimental mechanistic studies are challenging because these reactions involve multiple highly reactive intermediates and perplexing reaction pathways, engendering competing, but unverified, proposals for substrate conversions. Here, we report a comprehensive mechanistic study of photoredox nickel-catalyzed C-S cross-coupling based on time-resolved transient absorption spectroscopy, Stern-Volmer quenching, and quantum yield measurements. We have (i) discovered a self-sustained productive Ni(I/III) cycle leading to a quantum yield φ > 1; (ii) found that pyridinium iodide, formed in situ, serves as the dominant quencher for the excited state photocatalyst and a critical redox mediator to facilitate the formation of the active Ni(I) catalyst; and (iii) observed critical intermediates and determined the rate constants associated with their reactivity. Not only do the findings reveal a complete reaction cycle for C-S cross-coupling, but the mechanistic insights have also allowed for the reaction efficiency to be optimized and the substrate scope to be expanded from aryl iodides to include aryl bromides, thus broadening the applicability of photoredox C-S cross-coupling chemistry.
peri-Xanthenoxanthene (PXX): a Versatile Organic Photocatalyst in Organic Synthesis
Pezzetta, Cristofer,Folli, Andrea,Matuszewska, Oliwia,Murphy, Damien,Davidson, Robert W. M.,Bonifazi, Davide
supporting information, p. 4740 - 4753 (2021/04/09)
Recent years have witnessed a continuous development of photocatalysts to satisfy the growing demand of photophysical and redox properties in photoredox catalysis, with complex structures or alternative strategies devised to access highly reducing or oxidising systems. We report herein the use of peri-xanthenoxanthene (PXX), a simple and inexpensive dye, as an efficient photocatalyst. Its highly reducing excited state allows activation of a wide range of substrates, thus triggering useful radical reactions. Benchmark transformations such as the addition of organic radicals, generated by photoreduction of organic halides, to radical traps are initially demonstrated. More complex dual catalytic manifolds are also shown to be accessible: the β-arylation of cyclic ketones is successful when using a secondary amine as organocatalyst, while cross-coupling reactions of aryl halides with amines and thiols are obtained when using a Ni co-catalyst. Application to the efficient two-step synthesis of the expensive fluoro-tetrahydro-1H-pyrido[4,3-b]indole, a crucial synthetic intermediate for the investigational drug setipiprant, has been also demonstrated. (Figure presented.).
Heterogeneously Ni-Pd nanoparticle-catalyzed base-free formal C-S bond metathesis of thiols
Mitamura, Kanju,Yatabe, Takafumi,Yamamoto, Kidai,Yabe, Tomohiro,Suzuki, Kosuke,Yamaguchi, Kazuya
supporting information, p. 3749 - 3752 (2021/04/21)
This study rationally designed a heterogeneously catalyzed system (i.e., using Ni-Pd alloy nanoparticles supported on hydroxyapatite (Ni-Pd/HAP) under an H2atmosphere) achieving an efficient base-free formal C-S bond metathesis of various thiolsviasuppression of the Ni catalysis deactivation.
The energy-transfer-enabled biocompatible disulfide–ene reaction
Teders, Michael,Henkel, Christian,Anh?user, Lea,Strieth-Kalthoff, Felix,Gómez-Suárez, Adrián,Kleinmans, Roman,Kahnt, Axel,Rentmeister, Andrea,Guldi, Dirk,Glorius, Frank
, p. 981 - 988 (2018/08/31)
Sulfur-containing molecules participate in many essential biological processes. Of utmost importance is the methylthioether moiety, present in the proteinogenic amino acid methionine and installed in tRNA by radical-S-adenosylmethionine methylthiotransferases. Although the thiol–ene reaction for carbon–sulfur bond formation has found widespread applications in materials or medicinal science, a biocompatible chemo- and regioselective hydrothiolation of unactivated alkenes and alkynes remains elusive. Here, we describe the design of a general chemoselective anti-Markovnikov hydroalkyl/aryl thiolation of alkenes and alkynes—also allowing the biologically important hydromethylthiolation—by triplet–triplet energy transfer activation of disulfides. This fast disulfide–ene reaction shows extraordinary functional group tolerance and biocompatibility. Transient absorption spectroscopy was used to study the sensitization process in detail. The hereby gained mechanistic insights were successfully employed for optimization of the catalytic system. This photosensitized transformation should stimulate bioimaging applications and carbon–sulfur bond-forming late-stage functionalization chemistry, especially in the context of metabolic labelling.
Zinc-Catalyzed Synthesis of Dithioacetals through Double Hydrosulfenylation of Alkynes by Thiols
Taniguchi, Nobukazu,Kitayama, Kenji
, p. 2712 - 2716 (2018/12/14)
Zinc-catalyzed hydrosulfenylation of alkenes can be performed in various solvents, and the corresponding products are obtained regioselectively. Dihydrosulfenylation of alkynes with thiols can also be achieved by using a zinc catalyst, and the reaction is preferentially promoted over monohydrosulfenylation. The reaction can also give dithioacetals regioselectively in excellent yields.
Efficient dehydrative alkylation of thiols with alcohols catalyzed by alkyl halides
Yang, Yaqi,Ye, Zihang,Zhang, Xu,Zhou, Yipeng,Ma, Xiantao,Cao, Hongen,Li, Huan,Yu, Lei,Xu, Qing
supporting information, p. 9638 - 9642 (2017/11/30)
Alcohols can be efficiently converted into the useful thioethers by a transition metal- and base-free dehydrative S-alkylation reaction with thiols or disulfides by employing alkyl halides as the effective catalyst. This simple and efficient method is a green and practical way for the preparation of thioethers, as it tolerates a wide range of substrates such as aryl and alkyl thiols, as well as benzylic, allylic, secondary, tertiary, and even the less reactive aliphatic alcohols.
Photoredox Mediated Nickel Catalyzed Cross-Coupling of Thiols with Aryl and Heteroaryl Iodides via Thiyl Radicals
Oderinde, Martins S.,Frenette, Mathieu,Robbins, Daniel W.,Aquila, Brian,Johannes, Jeffrey W.
supporting information, p. 1760 - 1763 (2016/03/01)
Ni-catalyzed cross-couplings of aryl, benzyl, and alkyl thiols with aryl and heteroaryl iodides were accomplished in the presence of an Ir-photoredox catalyst. Highly chemoselective C-S cross-coupling was achieved versus competitive C-O and C-N cross-couplings. This C-S cross-coupling method exhibits remarkable functional group tolerance, and the reactions can be carried out in the presence of molecular oxygen. Mechanistic investigations indicated that the reaction proceeded through transient Ni(I)-species and thiyl radicals. Distinct from nickel-catalyzed cross-coupling reactions involving carbon-centered radicals, control experiments and spectroscopic studies suggest that this C-S cross-coupling reaction does not involve a Ni(0)-species.
Nickel-catalyzed C-S bond formation: Synthesis of aryl sulfides from arylsulfonyl hydrazides and boronic acids
Singh, Rahul,Allam, Bharat Kumar,Singh, Neetu,Kumari, Kumkum,Singh, Satish Kumar,Singh, Krishna Nand
supporting information, p. 1181 - 1186 (2015/04/22)
A practical nickel-catalysed approach has been developed for the C-S bond formation through the cross-coupling of arylsulfonyl hydrazides and aryl boronic acids. The report employs arylsulfonyl hydrazide as an aryl thiol equivalent and offers a mild and eco-safe synthesis of unsymmetrical thioethers in good to excellent yields in air. The scope and versatility of the method has been successfully demonstrated with 22 examples.
Ti(O-i-Pr)4/Me3SiCl/Mg-mediated reductive cleavage of sulfonamides and sulfonates to amines and alcohols
Shohji, Noriaki,Kawaji, Tsuyoshi,Okamoto, Sentaro
supporting information; experimental part, p. 2626 - 2629 (2011/07/08)
A low-valent titanium generated in situ from Ti(O-i-Pr)4, Me3SiCl, and Mg powder in THF reacted with aryl- and alkyl-sulfonamides of aryl and alkyl amines in a reductive N-S/S-O/S-C bond cleaving pathway to provide the corresponding amines and hydrocarbons (and thiols) derived from the sulfonyl moiety. The reagent could also cleave sulfonates to the corresponding alcohols.
Facile preparation of aryl sulfides using palladium catalysis under mild conditions
Okauchi, Tatsuo,Kuramoto, Kouji,Kitamura, Mitsuru
supporting information; experimental part, p. 2891 - 2894 (2011/02/28)
A convenient method for C-S cross-coupling of aryl bromides with various thiols has been developed that involves the use of a 1,1′- bis(diphenylphosphino)ferrocene (DPPF)-ligated palladium complex with N,N-diisopropylethylamine (DIPEA) as the base. This coupling is tolerant of a wide range of functional groups, including hydroxy, amino, cyano, nitro, formyl, and carboxyl groups. Georg Thieme Verlag Stuttgart - New York.
