7439-10-3Relevant articles and documents
Zn- And Cu-catalyzed coupling of tertiary alkyl bromides and oxalates to forge challenging C?O, C?S, and C?N bonds
Gong, Yuxin,Zhu, Zhaodong,Qian, Qun,Tong, Weiqi,Gong, Hegui
supporting information, p. 1005 - 1010 (2021/02/01)
We describe here the facile construction of sterically hindered tertiary alkyl ethers and thioethers via the Zn(OTf)2catalyzed coupling of alcohols/phenols with unactivated tertiary alkyl bromides and the Cu(OTf)2-catalyzed thiolation of unactivated tertiary alkyl oxalates with thiols. The present protocol represents one of the most effective unactivated tertiary C(sp3)? heteroatom bond-forming conditions via readily accessible Lewis acid catalysis that is surprisingly less developed.
Ni(II) Precatalysts Enable Thioetherification of (Hetero)Aryl Halides and Tosylates and Tandem C?S/C?N Couplings
Martín, M. Trinidad,Marín, Mario,Maya, Celia,Prieto, Auxiliadora,Nicasio, M. Carmen
supporting information, p. 12320 - 12326 (2021/08/09)
Ni-catalyzed C?S cross-coupling reactions have received less attention compared with other C-heteroatom couplings. Most reported examples comprise the thioetherification of most reactive aryl iodides with aromatic thiols. The use of C?O electrophiles in this context is almost uncharted. Here, we describe that preformed Ni(II) precatalysts of the type NiCl(allyl)(PMe2Ar’) (Ar’=terphenyl group) efficiently couple a wide range of (hetero)aryl halides, including challenging aryl chlorides, with a variety of aromatic and aliphatic thiols. Aryl and alkenyl tosylates are also well tolerated, demonstrating, for the first time, to be competent electrophilic partners in Ni-catalyzed C?S bond formation. The chemoselective functionalization of the C?I bond in the presence of a C?Cl bond allows for designing site-selective tandem C?S/C?N couplings. The formation of the two C-heteroatom bonds takes place in a single operation and represents a rare example of dual electrophile/nucleophile chemoselective process.
Scalable electrochemical reduction of sulfoxides to sulfides
Kong, Zhenshuo,Pan, Chao,Li, Ming,Wen, Lirong,Guo, Weisi
supporting information, p. 2773 - 2777 (2021/04/21)
A scalable reduction of sulfoxides to sulfides in a sustainable way remains an unmet challenge. This report discloses an electrochemical reduction of sulfoxides on a large scale (>10 g) under mild reaction conditions. Sulfoxides are activated using a substoichiometric amount of the Lewis acid AlCl3, which could be regeneratedviaa combination of inexpensive aluminum anode with chloride anion. This deoxygenation process features a broad substrate scope, including acid-labile substrates and drug molecules.
Deprotonated Salicylaldehyde as Visible Light Photocatalyst
Zhuang, Yan-Jun,Qu, Jian-Ping,Kang, Yan-Biao
, p. 4386 - 4397 (2020/03/05)
Salicylaldehyde is established as an efficient visible light photocatalyst for the first time. Compared to other simple aldehyde analogies, salicylaldehyde has a unique deprotonative red-shift from 324 to 417 nm and gives rise to the remarkable increase of fluorescence quantum from 0.0368 to 0.4632, thus enabling salicylaldehyde as a visible light (>400 nm) photocatalyst. The experimental investigations suggest that the reactive radical species are generated by sensitization of the substrates by the deprotonated salicylaldehyde through an energy-transfer pathway. Consequently, the C-C cleaving alkylation reactions of N-hydroxyphthalimide esters proceed smoothly in the presence of as low as 1 mol % of salicylaldehyde under the visible-light irradiation, affording desired alkylation products with up to 99% yields. Application in visible-light induced aerobic oxidation of N-alkylpyridinium salts is also reported.
Transalkylation of alkyl aryl sulfides with alkylating agents
Nawrot, Daria,Koleni?, Marek,Kune?, Ji?í,Kostelansky, Filip,Miletin, Miroslav,Novakova, Veronika,Zimcik, Petr
, p. 594 - 599 (2018/01/01)
The reaction of methyl iodide with tert-butylphenylsulfide in DMF leads to a transalkylation that produces methylphenylsulfide. This transalkylation reaction was further studied by 1H NMR spectroscopy. The polarity of the solvent, the electron density on the sulfur atom, and the strength of the alkylating agent (MeI, EtI, BuI, dimethyl sulfate, or dimethyl carbonate) played important roles in the reaction. The suggested mechanism of the reaction involves the formation of a dialkyl aryl sulfonium salt that subsequently eliminates the radical. This mechanism was supported by the observation of higher conversion rates for compounds with more branched alkyl groups on the sulfur atom, which may lead to the formation of more stable radicals.
C-S cross-coupling of aryl halides with alkyl thiols catalyzed by in-situ generated nickel(II) N-heterocyclic carbene complexes
Guo, Fang-Jie,Sun, Jing,Xu, Zhao-Qing,Kühn, Fritz E.,Zang, Shu-Liang,Zhou, Ming-Dong
, p. 11 - 14 (2017/03/24)
The C-S cross-coupling of aryl halides with alkyl thiols catalyzed by in-situ generated Ni (II) N-heterocyclic carbene (NHC) complexes is investigated. Good to excellent yields can be obtained for a variety of aryl halides when using 5 mol% of the Ni (II)-NHC catalyst and 1.5 eq. of KOtBu. Both the electronic and steric effects of the NHC ligands on the catalytic performance of Ni (II)-NHC, as well as the electronic effects of aryl halides on coupling reactivity are examined. The mechanism for Ni (II)-NHC catalyzed coupling reactions is also discussed.
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.
Tert-Butyl Sulfoxides: Key Precursors for Palladium-Catalyzed Arylation of Sulfenate Salts
Gelat, Fabien,Lohier, Jean-Fran?ois,Gaumont, Annie-Claude,Perrio, Stéphane
supporting information, p. 2011 - 2016 (2015/06/23)
The present report describes an efficient and clean generation of sulfenate salts (R1SO-) by pyrolysis of readily available tert-butyl sulfoxides to give sulfenic acids (R1SOH) and traceless isobutene, followed by hydrogen abstraction with a weak inorganic base (K3PO4). The relevance of this process was exemplified through an in situ palladium-catalyzed cross-coupling reaction with aryl halides/triflates leading to aryl sulfoxides. The operationally simple C-S bond-forming protocol developed uses Pd(dba)2 as catalyst and Xantphos as ligand in toluene or a toluene/H2O mixture. Further extensions include the use of di-tert-butyl sulfoxide as an equivalent for sulfur monoxide dianion (SO2-) and the development of diastereoselective versions in the [2.2]paracyclophane and biaryl series.
Catalytic C - S cross-coupling reactions employing Ni complexes of pyrrole-based pincer ligands
Venkanna, Gopaladasu T.,Arman, Hadi D.,Tonzetich, Zachary J.
, p. 2941 - 2950 (2015/02/19)
A series of catalytic C - S coupling reactions utilizing well-defined Ni(II) PNP pincer complexes as precatalysts are reported (PNP = anion of 2,5-bis[(dialkyl/aryl-phosphino)methyl]pyrrole, abbreviated as P2RPyr). Coupling reactions employing a variety of aryl iodides and thiols in the presence of base and DMF proceed in good to excellent yield at 80°C with low catalyst loadings. Aryl bromides were found to result in substantially lower yields, and aryl chlorides were found to be unreactive under the catalytic conditions. In an effort to further understand the reactivity of the nickel PNP precatalysts, complexes of Ni(II) containing amide, alkoxide, hydroxide, thiolate, and hydrosulfide ligands have been prepared and examined in stoichiometric reactions relevant to carbon-heteroatom coupling. Full characterization of each nickel complex is provided, including solid-state structures. The results of stoichiometric reactions implicate a reduced Ni(I) species as the active catalyst, which forms by reduction of the Ni(II) precatalyst in the presence of excess thiolate. The facility in forming Ni(I) species is invoked to rationalize the observed activity among different Ni PNP precatalysts. (Chemical Equation Presented).
Structural effects on the C-S bond cleavage in aryl tert -butyl sulfoxide radical cations
Cavattoni, Tullio,Del Giacco, Tiziana,Lanzalunga, Osvaldo,Mazzonna, Marco,Mencarelli, Paolo
, p. 4886 - 4894 (2013/07/11)
The oxidation of a series of aryl tert-butyl sulfoxides (4-X-C 6H4SOC(CH3)3: 1, X = OCH 3; 2, X = CH3; 3, X = H; 4, X = Br) photosensitized by 3-cyano-N-methylquinolinium perchlorate (3-CN-NMQ+) has been investigated by steady-state irradiation and nanosecond laser flash photolysis (LFP) under nitrogen in MeCN. Products deriving from the C-S bond cleavage in the radical cations 1+?-4+? have been observed in the steady-state photolysis experiments. By laser irradiation, the formation of 3-CN-NMQ? (λmax = 390 nm) and 1 +?-4+? (λmax = 500-620 nm) was observed. A first-order decay of the sulfoxide radical cations, attributable to C-S bond cleavage, was observed with fragmentation rate constants (k f) that decrease by increasing the electron donating power of the arylsulfinyl substituent from 1.8 × 106 s-1 (4 +?) to 2.3 × 105 s-1 (1 +?). DFT calculations showed that a significant fraction of the charge is delocalized in the tert-butyl group of the radical cations, thus explaining the small substituent effect on the C-S bond cleavage rate constants. Via application of the Marcus equation to the kinetic data, a very large value for the reorganization energy (λ = 62 kcal mol-1) has been calculated for the C-S bond scission reaction in 1+?-4 +?.
