- Ni(II) Precatalysts Enable Thioetherification of (Hetero)Aryl Halides and Tosylates and Tandem C?S/C?N Couplings
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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.
- Martín, M. Trinidad,Marín, Mario,Maya, Celia,Prieto, Auxiliadora,Nicasio, M. Carmen
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supporting information
p. 12320 - 12326
(2021/08/09)
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- Zn- And Cu-catalyzed coupling of tertiary alkyl bromides and oxalates to forge challenging C?O, C?S, and C?N bonds
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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.
- Gong, Yuxin,Zhu, Zhaodong,Qian, Qun,Tong, Weiqi,Gong, Hegui
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supporting information
p. 1005 - 1010
(2021/02/01)
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- Improved, odorless access to Benzo[1,2-d;4,5-d′]-bis[1,3]dithioles and tert-butyl arylsulfides via C-S cross coupling
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Benzo[1,2-d;4,5-d′]bis[1,3]dithioles are important building blocks within a range of functional materials such as fluorescent dyes, conjugated polymers, and stable trityl radicals. Access to these is usually gained via tert-butyl aryl sulfides, the synthesis of which requires the use of highly malodorous tert-butyl thiol and relies on SNAr-chemistry requiring harsh reaction conditions, while giving low yields. In the present work, S-tert-butyl isothiouronium bromide is successfully applied as an odorless surrogate for tert-butyl thiol. The C-S bond formation is carried out under palladium catalysis with the thiolate formed in situ resulting in high yields of tert-butyl aryl sulfides. The subsequent formation of benzo[1,2-d;4,5-d′]bis[1,3]dithioles is here achieved with scandium(III)triflate, a less harmful reagent than the usually used Lewis acids, e.g., boron trifluoride or tetrafluoroboric acid. This enables a convenient and environmentally more compliant access to high yields of benzo[1,2-d;4,5-d′]bis[1,3]dithioles.
- Fleck, Nico,Kopp, Kevin,Schiemann, Olav
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- Deprotonated Salicylaldehyde as Visible Light Photocatalyst
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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.
- Zhuang, Yan-Jun,Qu, Jian-Ping,Kang, Yan-Biao
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p. 4386 - 4397
(2020/03/05)
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- Surfactant-Type Catalyst for Aerobic Oxidative Coupling of Hydrazine with Thiol in Water
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A series of PEG-functionalized nitrogen ligands were developed to conduct an aerobic oxidative cross-coupling reaction between alkyl- or aryl-hydrazines with thiols in water. This surfactant-type catalyst enables high efficiencies and selectivities, while tolerating a large variety of functional groups. The mother liquor is still catalytically active after five runs.
- Ren, Xuanhe,Tang, Shanyu,Li, Longjia,Li, Jiao,Liang, Helong,Li, Ganzhong,Yang, Guanyu,Li, Heng,Yuan, Bingxin
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p. 8683 - 8690
(2019/07/08)
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- Method for synthesizing asymmetric sulfide from molecular oxygen oxidation water phase under catalysis of water-soluble transition metal compound
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Aiming at problems that in the prior art organic solvent pollution can be caused and a great number of reaction byproducts are generated when asymmetric sulfides are prepared, the invention disclosesa method for synthesizing an asymmetric sulfide from a molecular oxygen oxidation water phase under catalysis of a water-soluble transition metal compound. The method comprises the following steps: dispersing a sulfydryl compound and a hydrazine compound as substrates in a mole ratio of 1:1 into an alkali solution, and at 40-100 DEG C, in the presence of oxygen, and with a water-soluble transitionmetal compound as a catalyst, stirring to carry out reactions, thereby obtaining the asymmetric sulfide. By adopting the method, molecular oxygen is adopted as an oxidant, and water is adopted as a solvent, so that an organic solvent is avoided, a high yield can be achieved, and the problem of byproducts can be generally avoided.
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Paragraph 0069-0072
(2019/07/29)
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- Transalkylation of alkyl aryl sulfides with alkylating agents
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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.
- Nawrot, Daria,Koleni?, Marek,Kune?, Ji?í,Kostelansky, Filip,Miletin, Miroslav,Novakova, Veronika,Zimcik, Petr
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p. 594 - 599
(2018/01/01)
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- Tert-Butyl Sulfoxides: Key Precursors for Palladium-Catalyzed Arylation of Sulfenate Salts
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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.
- Gelat, Fabien,Lohier, Jean-Fran?ois,Gaumont, Annie-Claude,Perrio, Stéphane
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supporting information
p. 2011 - 2016
(2015/06/23)
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- Structural effects on the C-S bond cleavage in aryl tert -butyl sulfoxide radical cations
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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 +?.
- Cavattoni, Tullio,Del Giacco, Tiziana,Lanzalunga, Osvaldo,Mazzonna, Marco,Mencarelli, Paolo
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p. 4886 - 4894
(2013/07/11)
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- Nickel-mediated inter- and intramolecular C-S coupling of thiols and thioacetates with aryl iodides at room temperature
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A Ni(0)-catalyzed intermolecular cross-coupling of various functionalized thiols and aryl iodides has been developed and successfully extended to less explored intramolecular versions, where thioacetates could also be utilized as the strategic surrogate. Air-stable precatalysts, very mild conditions, and an easy protocol allow rapid access to medicinally useful aryl thioethers, as demonstrated in the facile synthesis of (±)-chuangxinmycin as a key step.
- Xu, Xiao-Bo,Liu, Jian,Zhang, Jian-Jian,Wang, Ya-Wen,Peng, Yu
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supporting information
p. 550 - 553
(2013/04/11)
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- One-pot synthesis of symmetrical and unsymmetrical aryl sulfides by Pd-catalyzed couplings of aryl halides and thioacetates
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Aryl sulfides were obtained from the coupling reaction of S-aryl (or S-alkyl) thioacetates and aryl bromides in the presence of palladium catalyst. This reaction method enables the one-pot synthesis of symmetrical and unsymmetrical diaryl sulfides by employing potassium thioacetate with aryl iodides and aryl bromides.
- Park, Namjin,Park, Kyungho,Jang, Mihee,Lee, Sunwoo
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experimental part
p. 4371 - 4378
(2011/07/06)
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- Resting state and elementary steps of the coupling of aryl halides with thiols catalyzed by alkylbisphosphine complexes of palladium
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Detailed mechanistic studies on the coupling of aryl halides with thiolscatalyzed by palladium complexes of the alkylbisphosphine ligand CyPF- t Bu (1-dicyclohexylphosphino-2-di-tert-butylphosphinoethylfer rocene) are reported. The elementary steps that constitute the catalyticcycle, i.e. oxidative addition, transmetalation and reductive eliminati on, have been studied, and their relative rates are reported. Each of the steps of the catalytic process occurs at temperatures that are much lower than those required for the reactions catalyzed by a combination of palladium precursors and CyPF- t Bu. To explain these differences in rates between the catalytic and stoichiometric reactions, studies were conducted to identify the resting state of the catalyst of the reactions catalyzed by a combination of Pd(OAc)2 and CyPF- t Bu, a combination of Pd(dba) 2 and CyPF- t Bu, or the likely intermediate Pd(CyPF- t Bu)(Ar)(Br). These data show that the major palladium complex in each case lies off of the catalytic cycle. The resting state of the reactions catalyzed by Pd(OAc) 2 andCyPF- t Bu was the palladium bis-thiolate complex [Pd(CyPF-t Bu)(SR) 2 ] (R = alkyl or aryl). The resting state in reactions catalyzed by Pd 2 (dba) 3 and CyPF- t Bu was the binuclear complex [Pd(CyPF t Bu)] 2 (μ 2 ,η 2 -dba) (9). The resting states of reactions of both aromatic and aliphatic thiols catalyzed by [Pd(CyPF- t Bu)(p-tolyl)(Br)] (3a) were the hydridopalladium thiolate complexes [Pd(CyPF- t Bu)(H)(SR)] (R= alkyl and aryl). All these palladium species have been prepared independently, and the mechanisms by which they enter the catalytic cycle have been examined in detail. These features of the reaction catalyzed by palladium and CyPF- t Bu have been compared with those of reactions catalyzed by the alkylbisphosphine DiPPF and Pd(OAc) 2 or Pd(dba) 2 . Our data indicate that the resting states of these reactions are similar to each otherand that our mechanistic conclusions about reactions catalyzed by palla dium and CyPF- t Bu can be extrapolated to reactions catalyzed by complexes of other electron-rich bisphosphines.
- Alvaro, Elsa,Hartwig, John F.
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supporting information; experimental part
p. 7858 - 7868
(2009/10/16)
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- A general and efficient method for the palladium-catalyzed cross-coupling of thiols and secondary phosphines
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The general and efficient cross-coupling of thiols with aryl halides was developed utilizing Pd(OAc)2/1,1′-bis(diisopropylphosphino) ferrocene as the catalyst. The substrate scope is broad and includes a variety of aryl bromides and chlorides,
- Murata, Miki,Buchwald, Stephen L.
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p. 7397 - 7403
(2007/10/03)
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- Carbon-sulfur bond-forming reductive elimination involving sp-, sp2-, and sp3-hybridized carbon. Mechanism, steric effects, and electronic effects on sulfide formation
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Palladium thiolato complexes [(L)Pd(R)(SR')], within which L is a chelating ligand such as DPPE, DPPP, DPPBz, DPPF, or TRANSPHOS, R is a methyl, alkenyl, aryl, or alkynyl ligand, and R' is an aryl or alkyl group, were synthesized by substitution or proton-transfer reactions. All of these thiolato complexes were found to undergo carbon-sulfur bond-forming inductive elimination in high yields to form dialkyl sulfides, diaryl sulfides, alkyl aryl sulfides, alkyl alkenyl sulfides, and alkyl alkynyl sulfides. Reductive eliminations forming alkenyl alkyl sulfides and aryl alkyl sulfides were the fastest. Eliminations of alkynyl alkyl sulfides were slower, and elimination of dialkyl sulfide was the slowest. Thus the relative rates for sulfide elimination as a function of the hybridization of the palladium-bound carbon follow the trend sp2 > sp >> sp3. Rates of reductive elimination were faster for cis-chelating phosphine ligands with larger bite angles. Kinetic studies, along with results from radical trapping reactions, analysis of solvent effects; and analysis of complexes with chelating phosphines of varying rigidity, were conducted with [Pd(L)(S-tert-butyl)(Ar)] and [Pd(L)(S- tert-butyl)(Me)]. Carbon-sulfur bond-forming reductive eliminations involving both saturated and unsaturated hydrocarbyl groups proceed by an intramolecular, concerted mechanism. Systematic changes in the electronic properties of the thiolate and aryl groups showed that reductive elimination is the fastest for electron deficient aryl groups and electron rich arenethiolates, suggesting that the reaction follows a mechanism in which the thiolate acts as a nucleophile and the aryl group an electrophile. Studies with thiolate ligands and hydrocarbyl ligands of varying steric demands favor a migration mechanism involving coordination of the hydrocarbyl ligand in the transition state.
- Mann, Grace,Baranano, David,Hartwig, John F.,Rheingold, Arnold L.,Guzei, Ilia A.
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p. 9205 - 9219
(2007/10/03)
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- Nickel-catalysed Substitutions of Aryl tert-Butyl Sulfones with Organometallic Reagents: Synthesis of ortho-Substituted Unsymmetrical Biaryls
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In the presence of a catalytic amount of a nickel salt, aryl tert-butyl sulfones react with aryl Grignard reagents to give biaryls.This reaction is used in conjunction with the powerful ortho-lithiation-directing ability of aryl tert-butyl sulfonyl groups to make unsymmetrical ortho-substituted biaryls.In certain cases, the substitution of an aryl alkylsulfonyl group by an organometallic reagent is possible without a transition metal catalyst.
- Clayden, Jonathan,Cooney, J. Jonathan A.,Julia, Marc
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