- An efficient and catalyst free methylthiolation of 4-(bromomethyl)-2H-chromen-2-ones with DMSO
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The first simple, metal free, and efficient protocol has been established for the methylthiolation of structurally diverse 4-bromomethyl-2H-chromen-2-ones using dimethyl sulfoxide (DMSO) as methylthiolation source at higher temperature. The experimental m
- Chougala, Bahubali M.,Samundeeswari,Holiyachi, Megharaja,Naik, Nirmala S.,Shastri, Lokesh A.,Sunagar, Vinay A
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- A nickel-catalyzed silylation reaction of alkyl aryl sulfoxides with silylzinc reagents
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Ni(PEt3)Cl2-catalyzed silylation of alkyl aryl sulfoxides with silylzinc reagents was carried out. This protocol allows alkyl aryl sulfoxides to convert to arylsilicon compounds under mild reaction conditions, tolerates a range of functional groups and is suitable for a wide scope of substrates.
- Li, Wei-Ze,Wang, Zhong-Xia
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supporting information
p. 5082 - 5086
(2021/06/21)
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- Remarkably Efficient Iridium Catalysts for Directed C(sp2)-H and C(sp3)-H Borylation of Diverse Classes of Substrates
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Here we describe the discovery of a new class of C-H borylation catalysts and their use for regioselective C-H borylation of aromatic, heteroaromatic, and aliphatic systems. The new catalysts have Ir-C(thienyl) or Ir-C(furyl) anionic ligands instead of the diamine-type neutral chelating ligands used in the standard C-H borylation conditions. It is reported that the employment of these newly discovered catalysts show excellent reactivity and ortho-selectivity for diverse classes of aromatic substrates with high isolated yields. Moreover, the catalysts proved to be efficient for a wide number of aliphatic substrates for selective C(sp3)-H bond borylations. Heterocyclic molecules are selectively borylated using the inherently elevated reactivity of the C-H bonds. A number of late-stage C-H functionalization have been described using the same catalysts. Furthermore, we show that one of the catalysts could be used even in open air for the C(sp2)-H and C(sp3)-H borylations enabling the method more general. Preliminary mechanistic studies suggest that the active catalytic intermediate is the Ir(bis)boryl complex, and the attached ligand acts as bidentate ligand. Collectively, this study underlines the discovery of new class of C-H borylation catalysts that should find wide application in the context of C-H functionalization chemistry.
- Chattopadhyay, Buddhadeb,Hassan, Mirja Md Mahamudul,Hoque, Md Emdadul
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supporting information
p. 5022 - 5037
(2021/05/04)
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- Synthesis of benzyl sulfidesviasubstitution reaction at the sulfur of phosphinic acid thioesters
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An ambident electrophilicity of phosphinic acid thioesters is disclosed. Unexpected carbon-sulfur bond formation took place in the reaction between phosphinic acid thioesters and benzyl Grignard reagents. The developed method for benzyl sulfides has a wide substrate scope and was applicable for the synthesis of a drug analog.
- Nishiyama, Yoshitake,Hosoya, Takamitsu,Yoshida, Suguru
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supporting information
p. 5771 - 5774
(2020/06/03)
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- Nucleophilic Amination and Etherification of Aryl Alkyl Thioethers
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A transition-metal-free protocol capable of synthesizing diarylated aniline derivatives is reported. This method could be further employed to prepare aryl alkyl ethers. A wide range of thioethers, anilines, as well as alcohols were tolerated thanks to the mild reaction conditions. The strength of our method was demonstrated by performing a gram-scale reaction (20 mmol) followed by conversion of the nitrile group into synthetically useful aldehyde, ketone, and carboxylic acid.
- Wang, Xia,Tang, Yue,Long, Cheng-Yu,Dong, Wen-Ke,Li, Chenchen,Xu, Xinhua,Zhao, Wanxiang,Wang, Xue-Qiang
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supporting information
p. 4749 - 4753
(2018/08/23)
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- Chemoenzymatic Deracemization of Chiral Sulfoxides
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The highly enantioselective enzyme methionine sulfoxide reductase A was combined with an oxaziridine-type oxidant in a biphasic setup for the deracemization of chiral sulfoxides. Remarkably, high ee values were observed with a wide range of substrates, thus providing a practical route for the synthesis of enantiomerically pure sulfoxides.
- Nosek, Vladimír,Mí?ek, Ji?í
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supporting information
p. 9849 - 9852
(2018/07/31)
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- Indium-catalyzed direct conversion of dibenzyl ethers to dibenzyl sulfides using elemental sulfur and a hydrosilane and its application to the preparation of benzyl selenides
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Described herein is a catalytic system composed of an indium(III) compound, a hydrosilane and an easily handled form of elemental sulfur (S8) that effectively and directly catalyzes the sulfidation of dibenzyl ethers to produce dibenzyl sulfides. This system could also be applied to selenium in a straightforward conversion to dibenzyl selenides.
- Sakai, Norio,Takada, Koji,Katayama, Masahiro,Ogiwara, Yohei
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supporting information
p. 791 - 793
(2018/06/12)
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- Nickel-Catalyzed Cross-Coupling Reaction of Aryl Sulfoxides with Arylzinc Reagents: When the Leaving Group is an Oxidant
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Nickel-catalyzed Negishi-type cross-coupling of aryl methyl sulfoxides with arylzinc reagents has been developed. By consuming the catalyst-oxidizing methanesulfenate anion through oxidative homocoupling of the arylzinc reagent, smooth catalyst turnover c
- Yamamoto, Keita,Otsuka, Shinya,Nogi, Keisuke,Yorimitsu, Hideki
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p. 7623 - 7628
(2017/11/14)
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- B(C6F5)3-Catalyzed Deoxygenation of Sulfoxides and Amine N-Oxides with Hydrosilanes
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An efficient strategy for the deoxygenation of sulfoxides and amine N-oxides by using B(C6F5)3 and hydrosilanes was developed. This method provided the corresponding aromatic and aliphatic products in good to high yields and showed good functional-group tolerance under mild conditions.
- Ding, Fangwei,Jiang, Yanqiu,Gan, Shaoyan,Bao, Robert Li-Yuan,Lin, Kaifeng,Shi, Lei
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p. 3427 - 3430
(2017/07/04)
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- Using CS2 to Probe the Mechanistic Details of Decarboxylation of Bis(phosphinite)-Ligated Nickel Pincer Formate Complexes
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The reaction of the formate complex {2,6-(R2PO)2C6H3}Ni(OCHO) (R = tBu, 5; R = iPr, 6) with CS2 shows first-order kinetics in nickel concentration and zero-order in [CS2/su
- Ma, Qiang-Qiang,Liu, Ting,Adhikary, Anubendu,Zhang, Jie,Krause, Jeanette A.,Guan, Hairong
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p. 4077 - 4082
(2017/01/10)
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- Synthesis of dibenzo[c,e]oxepin-5(7H)-ones from benzyl thioethers and carboxylic acids: Rhodium-catalyzed double C-H activation controlled by different directing groups
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A rhodium(III)-catalyzed cross-coupling of benzyl thioethers and aryl carboxylic acids through the two directing groups is reported. Useful structures with diverse substituents were efficiently synthesized in one step with the cleavage of four bonds (C-H, C-S, O-H) and the formation of two bonds (C-C, C-O). The formed structure is the privileged core in natural products and bioactive molecules. This work highlights the power of using two different directing groups to enhance the selectivity of a double C-H activation, the first of such examples in cross-oxidative coupling.
- Zhang, Xi-Sha,Zhang, Yun-Fei,Li, Zhao-Wei,Luo, Fei-Xian,Shi, Zhang-Jie
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supporting information
p. 5478 - 5482
(2015/04/27)
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- Efficient Oxidation of Sulfides to Sulfoxides and Deoxygenation of Sulfoxides over Carbonaceous Solid Acid
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Carbonaceous Solid Acid (CSA) was found to be a highly efficient, environmentally friendly, recyclable heterogeneous solid acid for the oxidation of sulfides and deoxygenation of sulfoxides, in good to excellent yields under mild reaction conditions.
- Atabaki, Fariborz,Abedini, Ebrahim,Shokrolahi, Arash
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p. 1169 - 1176
(2015/08/04)
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- Photoinduced One-Electron Oxidation of Benzyl Methyl Sulfides in Acetonitrile: Time-Resolved Spectroscopic Evidence for a Thionium Ion Intermediate
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The photo-oxidation of 4-methoxybenzyl methyl sulfide (1a), benzyl methyl sulfide (1b), and 4-cyanobenzyl methyl sulfide (1c) has been investigated in the presence of N-methoxy phenanthridinium hexafluorophosphate (MeOP+PF6-) under nitrogen in CH3CN. The steady-state photolysis experiments showed for the investigated sulfides exclusively the formation of the corresponding benzaldehyde as the oxidation product, reasonably due to a deprotonation of the sulfide radical cations. Photo-oxidation of 1a-1c occurs through an electron transfer process. Indeed, laser flash photolysis measurements showed an efficient formation of sulfide radical cations, detected in their dimeric form [(4-X-C6H4CH2SCH3)2+] at ≈520 nm. At longer delay times, the absorption of the dimer radical cation was replaced by an absorption band assigned to the (α-thio)benzyl cation (thionium ion, γmax = 420-400 nm), formed by oxidation of the benzyl radical and not by that of the (α-thiomethyl)benzyl radical, as expected if a Cα-H bond cleavage is operative. This finding highlights a particular stability of this kind of cation never reported before, even though its involvement in one-electron oxidation mechanisms of various sulfides has already been invoked. Density functional theory calculations allowed identification of a significant charge and spin delocalization involving both the phenyl ring and the sulfur atom of the radical cations.
- Bettoni, Marta,Del Giacco, Tiziana,Stradiotto, Marina,Elisei, Fausto
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p. 8001 - 8008
(2015/09/01)
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- Palladium(II)-catalyzed ortho -olefination of arenes applying sulfoxides as remote directing groups
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A novel palladium-catalyzed ortho-C(sp2)-H olefination protocol has been developed by the use of sulfoxide as the directing group. Importantly, relatively remote coordination can be accessed to achieve the ortho olefination of benzyl, 2-arylethyl, and 3-arylpropenyl sulfoxide substrates, and the olefinated sulfoxide can be easily transformed to other functionalities.
- Wang, Binjie,Shen, Chuang,Yao, Jinzhong,Yin, Hong,Zhang, Yuhong
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supporting information
p. 46 - 49
(2014/01/23)
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- METHOD FOR PREPARING 2-HYDROXYBUTYROLACTONE
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The invention relates to a method for preparing 2-hydroxybutyrolactone (2HBL) from a compound or its salt or its oligomers, said compound fitting formula (I) [in-line-formulae]CH3—S—CH2CH2CR1R2R3[/in-line-formulae]WhereinR1 represents HR2 represents a group selected from OH; OR4 and OCOR4 wherein R4 represents a group selected from linear, cyclic, alicyclic or branches alkyl groups having from 1 to 10 carbon atoms, and aryl groups having from 6 to 10 carbon atoms, optionally substituted with substituent(s) selected from linear or branched alkyl groups having from 1 to 10 carbon atoms, halogens and hydroxyl, amino, nitro and alkoxy groups having from 1 to 10 carbon atoms; and OSiRR′R″ wherein R, R′ and R″ are selected independently of each other from linear, cyclic, alicyclic or branched alkyl groups having from 1 to 10 carbon atoms, aryl groups having from 6 to 10 carbon atoms, optionally substituted with substituent(s) selected from linear or branched alkyl groups having from 1 to 10 carbon atoms, or R1 and R2 represent together ═O,R3 represents COOH or a COOR5 group wherein R5 represents a group selected from linear, cyclic, alicyclic or branched alkyl groups having from 1 to 10 carbon atoms, benzyl groups and benzyl groups substituted with one or two substituents selected from linear or branched alkyl groups having from 1 to 10 carbon atoms, halogens and hydroxyl, amino, nitro and alkoxy groups having from 1 to 10 carbon atoms, or R3 represents a cyano group,method according to whicha sulfonium of said compound is obtained, said sulfonium fitting the formula (II) [in-line-formulae][CH3][CH2CH2CR1R2CR3][CR6R7R8]S+X?[/in-line-formulae]wherein R1, R2 and R3 have the above definition, and R6 and R7 are selected independently of each other from H, linear, cyclic, alicyclic or branched alkyl groups having from 1 to 10 carbon atoms, and aryl groups having from 6 to 10 carbon atoms, optionally substituted with substituent(s) selected from linear or branched alkyl groups having from 1 to 10 carbon atoms, halides and hydroxyl, amino, nitro and alkoxy groups having from 1 to 10 carbon atoms; R8 is selected from H, linear, cyclic, alicyclic or branched alkyl groups having from 1 to 10 carbon atoms, aryl groups having from 6 to 10 carbon atoms, optionally substituted with substituent(s) selected from linear or branched alkyl groups having from 1 to 10 carbon atoms, and attractor groups notably those comprising a function selected from acid, ester, cyano functions and X represents a counter-ion, andthe thereby obtained sulfonium is hydrolyzed and2,4-dihydroxybutyric acid or its salt is cyclized into 2-hydroxybutyrolactone.
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Paragraph 0081; 0082; 0092-0105
(2013/08/15)
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- Enantioselective nitrene transfer to sulfides catalyzed by a chiral iron complex
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Iron works: Enantioselective nitrene transfer to sulfide was accomplished by a chiral iron(III)/PyBOX catalyst (see scheme). Various sulfimides were thus obtained in high enantioselectivities and yields. Applications of this protocol to the syntheses of enantioenriched sulfoximines and an epoxide were also demonstrated. Copyright
- Wang, Jun,Frings, Marcus,Bolm, Carsten
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supporting information
p. 8661 - 8665
(2013/09/12)
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- One-pot synthesis of alkyl styryl sulfides free from transition metal/ligand catalyst and thiols
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A new protocol for the one-pot synthesis of styryl alkyl sulfides was developed. This methodology involves the in situ generation of thiolate anions by nucleophilic substitution between potassium thioacetate and alkyl halides followed by fragmentation. Further reactions of these thiolate anions with substituted (E,Z)-β-styryl halides gave the corresponding sulfides with retention of stereochemistry in good to excellent yields. This procedure does not require a metal catalyst, it proceeds under mild conditions and in short times, and it is free from malodorous and air-sensitive alkyl thiols. Copyright
- Heredia, Adrian A.,Penenory, Alicia B.
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p. 991 - 997
(2013/03/14)
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- Iodine-mediated thioetherification of alcohols with disulfides or NaSh under microwave irradiation
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An efficient and novel method for the thioetherification of an alcohol with disulfides or NaSH under microwave irradiation is presented. In the presence of iodine, a variety of alcohols were smoothly S-alkylated with disulfides or NaSH to give the corresponding thioethers in moderate to excellent yields. Copyright
- Hu, Bolun,Sun, Leilei,Tang, Riyuan,Hu, Huanan
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p. 2556 - 2562,7
(2020/09/16)
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- Ionic liquids - Promoted S-methylation of thiols utilizing dimethyl carbonate
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Convenient and efficient S-methylation of mercaptans or thiophenols occurs with dimethyl carbonate (DMC) in room temperature ionic liquids (RTILs) [Bmim]Cl. [Bmim]Cl can be recycled in four subsequent runs with only a gradual decrease in activity. A possible mechanism of this transformation is also discussed. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file. Copyright Taylor & Francis Group, LLC.
- Xie, Jiangang,Wu, Chengyao,Christopher, Branford White,Quan, Jing,Zhu, Limin
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experimental part
p. 31 - 37
(2011/04/22)
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- Deoxygenation of sulfoxides and reductive coupling of sulfonyl chlorides, sulfinates and thiosulfonates using Silphos [PCl3-n(SiO 2)n] as a heterogeneous phosphine reagent
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Deoxygenation of sulfoxides to thioethers and reductive coupling of sulfonyl chlorides, sodium sulfinates and thiosulfonates to their corresponding disulfides were carried out by a heterogeneous phosphine reagent, Silphos [PCl3-n(SiO2)n] and molecular I2 in dry refluxing MeCN in high yields. Georg Thieme Verlag Stuttgart.
- Iranpoor, Nasser,Firouzabadi, Habib,Jamalian, Arezu
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p. 1447 - 1449
(2007/10/03)
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- Solid state S-methylation of thiols and O-methylation of phenols and naphthols with dimethyl sulfate under microwave irradiation
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Mild and efficient S-methylation of thiols and o-methylation of phenols and naphthals occurs with dimethyl sulfate (DMS) supported on basic alumina under microwave irradiation in solventless system. Copyright Taylor & Francis Inc.
- Heravi, Majid M.,Ahari, Neda Zamani,Oskooie, Hossein A.,Ghassemzadeh, Mitra
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p. 1701 - 1712
(2007/10/03)
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- Oxidation of benzylic bromides by DMSO in the presence of zinc salts: A new variant of Kornblum's method
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Benzyl and 1-phenylethyl bromides are oxidised to benzaldehyde and acetophenone respectively by DMSO in the presence of zinc salts with moderate to high yield. The corresponding alcohol and the thiomethyl ether derivative are formed as by-products. However, 2-phenylethyl bromide affords, under forcing conditions, the corresponding thiomethyl ether and alcohol as major products. This study, besides leading to a new variant of Kornblum oxidation, has given an insight into its mechanism.
- Subrahmanya Bhat,Srinivas,Srinivas,Gurudutt
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p. 426 - 429
(2007/10/03)
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- Stereoselective reductase-catalysed deoxygenation of sulfoxides in aerobic and anaerobic bacteria.
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Direct and indirect evidence, of unexpected stereoselective reductase-catalysed deoxygenations of sulfoxides, was found. The deoxygenations proceeded simultaneously, with the expected dioxygenase-catalysed asymmetric sulfoxidation of sulfides, during some biotransformations with the aerobic bacterium Pseudomonas putida UV4. Stereoselective reductase-catalysed asymmetric deoxygenation of racemic alkylaryl, dialkyl and phenolic sulfoxides was observed, without evidence of the reverse sulfoxidation reaction, using anaerobic bacterial strains. A purified dimethyl sulfoxide reductase, obtained from the intact cells of the anaerobic bacterium Citrobacter braakii DMSO 11, yielded, from the corresponding racemates, enantiopure alkylaryl sulfoxide and thiosulfinate samples.
- Boyd, Derek R,Sharma, Narain D,King, Alistair W T,Shepherd, Steven D,Allen, Christopher C R,Holt, Robert A,Luckarift, Heather R,Dalton, Howard
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p. 554 - 561
(2007/10/03)
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- A gentle and efficient route for the deoxygenation of sulfoxides using catecholborane (HBcat; cat = 1,2-O2C6H4)
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The addition of catecholborane (HBcat; cat = 1,2-O2C 6H4) to a wide range of sulfoxides affords the corresponding sulfides, dihydrogen, and catBOBcat. The addition of catecholborane (HBcat; cat = 1,2-O2C6H4) to a wide range of sulfoxides affords the corresponding sulfides, dihydrogen, and catBOBcat. The diboron compound catBOBcat acts like a Lewis acid and will coordinate one molecule of the starting sulfoxide. Although deoxygenations with bulky or electron withdrawing sulfoxides are slow, these reactions can be greatly accelerated with the use of excess HBcat or by employing a rhodium catalyst.
- Harrison, Daniel J.,Tam, Nga Chiu,Vogels, Christopher M.,Langler, Richard F.,Baker, R. Thomas,Decken, Andreas,Westcott, Stephen A.
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p. 8493 - 8496
(2007/10/03)
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- A new approach to the reduction of sulfoxides to sulfides with 1,3-dithiane in the presence of electrophilic bromine as catalyst
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A new, mild, and novel method is described for the efficient deoxygenation of sulfoxides to their corresponding sulfides with 1,3-dithiane at room temperature in the presence of catalytic amounts of N-bromosuccinimide (NBS), 2,4,4,6-tetrabromo-2,5-cyclohexadienone (TABCO), or Br2 as the source of electrophilic bromine.
- Iranpoor, Nasser,Firouzabadi, Habib,Shaterian, Hamid Reza
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p. 2826 - 2830
(2007/10/03)
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- Reactions of 5-(alkyl)thianthrenium and other sulfonium salts with nucleophiles
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A series of 5-(alkyl)thianthrenium triflates (3a-d, g-i) with alkyl (R) groups Me (a), Et (b), isoPr (c), 2-Bu (d), cyclopentyl (g), cyclohexyl (h) and cycloheptyl (i) were prepared by alkylation of thianthrene (Th) with alkyl formate and trifluoromethanesulfonic (triflic) acid. Benzylation (3f) was achieved with benzyl bromide and silver triflate. 5-(Neopentyl)thianthrenium perchlorate (3e) was prepared by reaction of thianthrene cation radical perchlorate with dineopentyl mercury. Methyl- (4a) and cyclohexyldiphenylsulfonium triflate (4b) were made by alkylation of diphenyl sulfide. Benzyldimethyl- (5a), dibenzylmethyl- (5b) and benzylmethylphenylsulfonium perchlorate (5c) were prepared in standard ways. Reactions of these sulfonium salts with iodide ion and thiophenoxide ion were studied for comparison with our earlier reported reactions of comparable 5-(alkoxy)thianthrenium and methoxydiphenylsulfonium salts. It is deduced that reactions of 3-5 with nucleophiles (Nu-) I- and PhS- follow traditional SN2 and E2C paths. Thus, the salts 3a-c, e and f gave virtually quantitative yields of RNu and Th, while small amounts of butene(s) were obtained from 3d. The cycloalkyl salts 3g-i gave amounts of cycloalkylNu and cycloalkene typical of competition of SN2 and E2C routes in the classical reactions of cycloalkyl halides and tosylates with I- and PhS- ions. Whereas 4a gave only SN2 products, 4b gave SN2 and E2C products typical of SN2/E2C competition. Among the salts 5a-c displacement of the benzyl group was dominant (5a) or exclusive (5b, c), thus exhibiting the preferential displacement of a benzyl group that has been fully documented in earlier studies of SN2 reactions. Qualitative comparison showed that 3a (methyl) reacted much faster than 3e (neopentyl) with PhS-. Unlike alkoxysulfonium salts, the salts 3-5 do not appear to undergo reactions at the sulfonium sulfur atom. Copyright
- Liu, Bo,Shine, Henry J.
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- Deoxygenation of sulfoxides to thioethers by molybdenum pentachloride (MOCL5) and reductive coupling of sulfonyl chlorides to disulfides
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Molybdenum pentachloride (MoCl5) in the presence of Nal in dry acetonitrile or zinc powder in anhydrous THF converts sulfoxides to their thioethers in high yields. Sulfonyl chlorides can be readily reduced to their corresponding disultides with MoCl5/Nal/MeCN at room temperature or with MoCl5/Zn/MeCN under reflux conditions in high yields.
- Firouzabadi,Jamalian
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p. 211 - 220
(2007/10/03)
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- Substituent-dictated partitioning of intermediates on the sulfide singlet oxygen reaction surface. A new mechanism for oxidative C-S bond cleavage in α-hydroperoxy sulfides
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The reactions of singlet oxygen with 17 sulfides bearing either anion or radical stabilizing substituents are reported. The abilities of substituents to modify product compositions in both the oxidative cleavage and sulfide oxidation pathways are analyzed in terms of partitioning of the hydroperoxy sulfonium ylide intermediate. Evidence is presented that suggests that the hydroperoxy sulfonium ylide exists in both diradical and zwitterionic forms. In addition, both inter- and intramolecular pathways for decomposition of α-hydroperoxy sulfides are suggested to rationalize the substituent-dependent formation of oxidative C-S bond cleavage products.
- Toutchkine,Aebisher,Clennan
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p. 4966 - 4973
(2007/10/03)
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- Origin of the Stereoselectivity in (Ethoxycarbonyl)-, Cyano-, and Phenyl-Substituted (Arylsulfinyl)methyl Radicals
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An explanation for the very high diastereoselectivity observed for the reactions of carbonyl-substituted (arylsulfmyl)methyl radicals is presented, based on experimental results and semiempirical calculations. The influence of dipole-dipole interactions, allylic 1,3-strain(A1,3 strain), allylic 1,2-strain (A1,3 strain), and coulombic interactions is discussed based on stereoselectivities observed with (alkoxycarbonyl)-, cyano-, and aryl-substituted (arylsulfinyl)methyl radicals. In the second part, the effect of solvents and Lewis acids on the stereoselectivity of. reactions of (arylsulfmyl)- and (alkylsulfinyl)benzyl radicals has been examined.
- Renaud, Philippe,Bourquard, Thierry,Carrupt, Pierre-Alain,Gerster, Michèle
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p. 1048 - 1063
(2007/10/03)
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- Potassium fluoride on alumina: A convenient synthesis of O-alkyl methyldithiocarbonates. Pyrolysis of O-benzyl-S-methyldithiocarbonates
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Xanthates were easily prepared by adsorption of alcohol on KF-Al2O3 followed by treatment of carbon disulfide and iodomethane at room temperature. Pyrolysis of benzyl xanthate affords to a complex mixture of products. A radical process was proposed to explain the nature of products obtained.
- Villemin, Didier,Hachemi, Messaoud
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p. 2449 - 2459
(2007/10/03)
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- Arene-catalysed lithiation of triflates and triflamides under Barbier-type conditions: An indirect transformation of alcohols and amines into organolithium compounds
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The reaction of alkyl triflates 1 or benzyl triflamides 3 with an excess of lithium powder and a catalytic amount of naphthalene (4 mol%) in the presence of different electrophiles [Me3SiCl, Pr(i)CHO, Bu(t)CHO, PhCHO, 4-MeOC6H4-CHO, CH3(CH2)6CHO, Et2CO, (CH2)5CO, (c-C3H5)2CO, PhCOMe, 4-MeC6H4COPh, PhCh=NPh, n-C8H7CON(CH2)4] in THF at temperature ranging between -78 and 0°C leads, after hydrolysis with water, to the corresponding condensation products 2. When α,β-unsaturated carbonyl compounds are used as electrophilic compounds 1,2- (3-cyclohexenone) or 1,4-addition (cinnamaldehyde or benzylideneacetone) takes place depending on the electrophile used.
- Alonso, Emma,Ramon, Diego J.,Yus, Miguel
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p. 14341 - 14348
(2007/10/03)
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- Reductive α-substitution of sulfoxides with grignard reagents promoted by a magnesium amide
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The reactions of sulfoxides bearing α-hydrogen(s) (RSOCHR1R2: R-alkyl or aryl; R1, R2 = H, alkyl, or aryl) with Grignard reagents (R3MgBr: R3 = Et, Ph, or vinyl) in the presence of the diisopropylaminomagnesium reagent, generated in situ by the treatment of diisopropylamine with the appropriate Grignard reagents in diethyl ether, have resulted in the formation of the corresponding sulfides (RSCR1R2R3) in moderate to good isolated yields.
- Kobayashi, Kazuhiro,Yokota, Kouichi,Akamatsu, Hideki,Morikawa, Osamu,Konishi, Hisatoshi
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p. 441 - 443
(2007/10/03)
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- BIOTRANSFORMATION OF ORGANIC SULFIDES. PART 6. FORMATION OF CHIRAL para-SUBSTITUTED BENZYL METHYL SULFOXIDES BY HELMINTHOSPORIUM SPECIES NRRL 4671
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The fungus Helminthosporium species NRRL 4671 has been used for the biotransformation of a series of para-substituted benzyl sulfides with substituent groups consisting of trifluoromethyl, halo, hydroxy, methoxy, acetoxy, nitro, cyano, amino, acetamido, acyl and carboxylic acid units.In all cases, sulfoxide formation occurred in good yoeld and with predominant (S) chirality at the sulfur position.A minor amount of sulfone product was also obtained from the halo- and methoxy-substituted substrates.
- Holland, Herbert L.,Brown, Frances M.,Larsen, Brett G.
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p. 1561 - 1568
(2007/10/02)
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- Direct transformation of dialkyl sulfates into alkyllithium reagents by a naphthalene-catalysed lithiation
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The lithiation of primary and secondary dialkyl sufates with an excess of lithium powder in the presence of a catalytic amount of naphthalene (4 mol %) in THF at -78°C leads to the corresponding alkyllithium reagents (1:2 molar ratio) which react with different electrophiles, mainly carbonyl compounds, to yield after hydrolysis, the expected coupling products. This methodology represents an indirect way to transform alcohols into organolithium compounds through the corresponding dialkyl sulfates. When the same procedure is applied to five or six member cyclic sulfates (derived from 1,2- or 1,3-diols) only products arising from a β- or γ-elimination process (giving olefins or cyclopropanes), respectively, are obtained.
- Guijarro, David,Guillena, Gabricia,Mancheno, Balbino,Yus, Miguel
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p. 3427 - 3436
(2007/10/02)
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- Superelectrophilic methylthiomethylation of aromatics with chloromethyl methyl sulfide/aluminum chloride (MeSCH2Cl:2 AlCl3) reagent
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Effective methylthiomethylation of aromatics was achieved by using chloromethyl methyl sulfide/aluminum chloride (MeSCH2Cl:2 AlCl3) as the alkylating agent. Excess aluminum chloride activates the thiocarboxonium ion intermediate by coordinating with sulfur and thus diminishes back donation of 'electron density' into the carbocationic center, rendering it a superelectrophilic methylthiomethylating agent.
- Olah,Wang,Neyer
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p. 276 - 278
(2007/10/02)
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- Reactions of Triphenylphosphine with Di-, Tri-, or Tetrasulphides, or with Sulphur, in Hydroxylic Solvents.
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In contrast to the behaviour of disulphides RS2R, the mono-desulphurisation of tri- or tetra-sulphides RSnR (R = benzyl, p-tolyl; n= 3, 4) by triphenylphosphine in hydroxylic solvents (methanol-benzene or water- 2-propanol-benzene) mainly affords Ph3PS with only small (n = 3) or very small (n = 4) amounts of Ph3PO.Ph3PO was virtually absent in the reaction products of Ph3P with 2Sn (n = 2, 3) or with elemental sulphur in alcoholic or aqueous media.Reaction rates for the formation of Ph3PS or Ph3PO decrease in the order: RS4R > RS3R >> RS2R (R = benzyl or p-tolyl) and hydroxylic >> aprotic solvents; the dependence on R is: (EtO)2P(S) >> p-tolyl > benzyl.Addition of a thiol impedes the formation of Ph3PO; low pH's have an opposite effect.The results are rationalised in terms of basicity of anions RSp- (p = 1 to n-1), relative softness of terminal or central S in RSnR and Broensted acidity of the solvent.An alternative is proposed to the Bartlett's mechanism for the reaction of S8 with Ph3P, in which the intermediate zwitterion Ph3P+S4- collapses by fast intramolecular nucleophilic displacement, affording Ph3PS and highly reactive S7.
- Demarcq, Michel C.
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p. 3052 - 3080
(2007/10/02)
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- Alkali-metal-ion-assisted BAL2 cleavage of 2-(methoxycarbonyl)-1,3-xylylene-18-crown-5 by benzenemethanethiolate anion
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BAL2 demethylation of 2-(methoxycarbonyl)-1,3-xylylene-18-crown-5 by benzenemethanethiolate anion in dimethylformamide (+1.6 M water) at 35 deg C is significantly promoted by alkali-metal counterions, the efficiency order being Na(1+) > K(1+) > Cs(1+) >Li(1+).The contrasting behaviour of the model compound, methyl 2,6-dimethylbenzoate, whose demethylation reaction is in fact slightly inhibited by metal ions, points to the crucial role played by the polyether bridge of the crown ether substrate.In line with previous work from this laboratory, selectivetransition-state stabilisation in the metal-ion-promoted cleavage of the crown-ether substrate is ascribed to a favourable combination of electrostatic binding of the metal ions with the negative charge being transferred from the nucleophile to the convergent methoxycarbonyl group and coordinative binding to the neutral donors of the polyether bridge.
- Cacciapaglia, R.,Mandolini, L.,Castelli, V. Van Axel
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p. 347 - 350
(2007/10/02)
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- Naphthalene-catalysed lithiation of dialkyl sulfates: A new route for organolithium reagents
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The lithiation of primary and secondary dialkyl sulfates with an excess of lithium powder in the presence of a catalytic amount of naphthalene at -78°C leads to the corresponding alkyl-lithium reagents (1:2 molar ratio), which react with different electrophiles, mainly carbonyl compounds, to yield the expected coupling products. This methodology represents an indirect way for transforming alcohols into organolithium compounds through the corresponding dialkyl sulfates.
- Guijarro,Mancheno,Yus
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p. 5597 - 5600
(2007/10/02)
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- GENERATION OF CHALCOGENIDE ANIONS IN HYDRAZINE HYDRATE MEDIUM
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Aromatic thiols and dichalcogenides in hydrazine hydrate are effective generators of chalcogenide ions that will react with organyl halides to form diorganyl chalcogenides.Alkanethiols and dialkyl dichalcogenides are less effective in reaction with organyl chalcogenides.
- Turchaninova, L. P.,Korchevin, N. A.,Deryagina, E. N.,Trofimov, B. A.,Voronkov, M. G.
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p. 125 - 126
(2007/10/02)
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- Mechanism of Reaction of S,S-Diphenyl-S-methoxythiazyne with Thiole
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The reaction of S,S-diphenyl-S-methoxythiazyne with various thiols gave methyl sulfides.Kinetic investigations support a mechanism involving an initial protonation of the thiazyne nitrogen with thiol followed by a nucleophilic attack of thiolate anion on the methyl group.
- Yoshimura, Toshiaki,Tsukurimichi, Eiichi,Sugiyama, Yasuhisa,Kita, Hiroshi,Shimasaki, Choichiro,Hasegawa, Kiyoshi
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p. 3176 - 3178
(2007/10/02)
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- SYNTHETIC USEFULNESS OF SILYL THIOKETONES: FUNCTIONALIZATION OF THEIR PRIMARY ADDUCTS THROUGH DESILYLATION AND TRAPPING BY CARBON ELECTROPHILES.
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Desilylation of either α-silyl sulphides or silyl dihydrothiopyrans (easily obtained from silyl thiones as primary adducts), when performed in the presence of carbon electrophiles (aldehydes or ketones), offers an easy entry to carbofunctionalised products.
- Bonini, Bianca F.,Masiero, Stefano,Mazzanti, Germana,Zani, Paolo
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p. 815 - 818
(2007/10/02)
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- Mild and efficient deoxygenation of sulfoxides with titanium(IV) chloride/sodium iodide reagent system
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Dialkyl, diaryl and alkyl aryl sulfoxides were readily deoxygenated to the corresponding sulfides in excellent yields with titanium(IV) chloride/sodium iodide reagent system at room temperature.
- Balicki
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p. 155 - 156
(2007/10/02)
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- A Facile Synthesis of Unsymmetrical Sulfides under Phase Transfer Conditions
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An efficient synthesis of unsymmetrical sulfides (3) is described by reacting S-alkylisothiouronium salts (1) with alkyl halides (2) under liquid-liquid phase transfer catalyst conditions.
- Hengchang, Chen,Zhenzhong, Liu,Wei, Liu
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p. 3313 - 3316
(2007/10/02)
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- Reduction of Sulfoxides with Sodium or Benzyl Bromide
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The reduction of dimethyl and diphenyl sulfoxides, and of alkyl and arylbenzyl sulfoxides to the corresponding sulfides can be carried out using sodium bromide without solvent or benzyl bromide in dimethylformamide, mostly through an oxidation-reduction cycle catalyzed by developing hydrobromic acid.
- Bernard, Angela M.,Caredda, Maria G.,Piras, P. Paolo,Serra, Ermanno
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p. 329 - 330
(2007/10/02)
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- Electronic and steric effects in the dissociative displacement of thioethers from mixed phenyl(thioether)platinum(II) complexes
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A series of compounds of the type cis-[PtPh2L2], where L encompasses a wide range of thioethers of different steric and electron-donating characteristics, have been prepared and characterized. Most of these monomeric compounds exist in solution in equilibrium with the sulfur-bridged dimer [Pt2Ph4(μ-L)2] and the free thioether. Addition of small amounts of ligand in solution allows the stabilization of the monomeric form. Kinetic studies of the displacement of the thioethers with 2,2′-bipyridine (bpy) to yield [PtPh2(bpy)] in CH2Cl2 at 298.16 K, carried out in the presence of sufficient excess of [L] and [bpy] to ensure pseudo-first-order conditions, showed that the reactions follow a bivariate nonlinear rate law kobsd = a[bpy]/(b[L] + [bpy]) + c[bpy], which has the same form as that of similar systems for which a dissociative mechanism has been proposed. The reactivity decreases linearly with increasing σ-donor ability of the leaving thioether, with bulky substituents on sulfur playing an accelerating role. The relative sensitivities of the dissociative and associative processes to the inductive effects of the leaving group are compared and related to the degree of lengthening and weakening of the bond with the metal produced by the trans-activating group.
- Alibrandi, Giuseppe,Minniti, Domenico,Scolaro, Luigi Monsù,Romeo, Raffaello
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p. 1939 - 1943
(2008/10/08)
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- SYNTHESIS OF SUBSTITUTED TRANS-1,6-DIMETHYLBICYCLONON-2-ENES USING A CLAISEN REARRANGEMENT OF α-(THIOALKOXY)ESTERS
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The Claisen rearrangement of α-(thioalkoxy)esters provided access to substituted trans-1,6-dimethylbicyclonon-2-enes characteristic of the CD rings of the cucurbitanes.
- Richardson, Stewart K.,Sabol, Mark R.,Watt, David S.
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p. 359 - 368
(2007/10/02)
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- NOVEL AND EFFECTIVE METHODS FOR α-THIOALKYLATION OF AROMATIC COMPOUNDS
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Convenient and effective methods for the introduction of a methylthiomethyl group and other α-thioalkyl group into aromatic compounds are described.
- Torisawa, Yasuhiro,Satoh, Atsushi,Ikegami, Shiro
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p. 1729 - 1732
(2007/10/02)
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- The use of aminoiminomethanesulfinic acid (thiourea dioxide) under phase transfer conditions for generating organochalcogenate anions. Synthesis of sulfides, selenides and tellurides
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A procedure is described which allows for the in situ synthesis of arylalkyl, diaryl and dialkylchalcogenides under phase transfer conditions starting from the corresponding diorganodichalcogenides.The dichalcogenides are reduced by aminoiminomethanesulfinic acid (thiourea dioxide) in alkaline medium and catalyzed by a quaternary ammonium salt.The reduction proceeds easily for diaryl disulfides and diaryl diselenides at a sodium hydroxide concentration of 13percent; diaryl ditellurides require a 50percent sodium hydroxide solution to give the aryl tellurolate anion.The dialkyl diselenides and dialkyl ditellurides are more difficult to reduce.The intermediate arylthiolates and arylselenolates are quenched by alkyl and activated aryl halides to give the corresponding sulfides and selenides in high yield (77-97percent).The aryltellurolates react with alkyl halides giving the aryl alkyl tellurides in 81-96percent yield.The procedure could not be successfully used for the synthesis of dialkylselenides and dialkyl tellurides; low yields and mixture of products were formed.
- Comasseto, J. V.,Lang, E. S.,Ferreira, J. Tercio B.,Simonelli, F.,Correira, V. R.
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p. 329 - 340
(2007/10/02)
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- Chemoselective reaction of a sulfonate ester with methoxide ions in preference to benzyl mercaptide anions
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Trifluoroethyl benzyl sulfide was prepared (in 2-propanol) and subsequently chlorinated as a further test of substituent electronegativity based regiochemical predictions.The initial attempt to prepare that sulfide by reaction of 2,2,2-trifluoroethyl methanesulfonate and benzyl mercaptide anions (in methanol) furnished benzyl methyl sulfide.Mechanistic possibilities are discussed in detail and some synthetic consequences of this novel reaction are presented.
- Langler, Richard Francis,Morrison, Nancy Ann
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p. 2385 - 2389
(2007/10/02)
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- THIOALKYLTRIBUTYL- AND THIOALKOXYTRIPHENYLPHOSPHONIUM SALTS: PREPARATION AND APPLICATION TO THE SYNTHESIS OF THIOLESTERS AND UNSYMMETRICAL SULFIDES
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Thioalkoxyphosphonium salts, Ph3PSR(1+)*ClO4(1-) (3) and Bu3PSR(1+)*X(1-) (X=ClO4 and BF4) (5), have been prepared from the corresponding tertiary phosphines and disulfides by simple procedures, which involve (i) constant current electrolysis in acetonitrile in the presence of either HClO4 (for 3) or PhCOOH and LiX (for 5), and (ii) stirring an equimolar mixture of a phosphine, a disulfide, PHCOOH, and LiX in acetonitrile at ambient temperature.For the preparation of 3, which have been reported as useful reagents for the synthesis of unsymmetrical disulfides, the electrochemical method is recomended, while for 5 the latter non-electrochemicl procedure gave better results.Reactions of the phosphonium salts 5 with carboxylic acidsand primary alcohols in benzene at ambient temperature gave thiolesters and unsymmetrical sulfides, respectively, in fair to excellent yields.Keywords - triphenylphosphine; tributylphosphine; disulfide; thioalkoxyphosphonium salt; thiolester; unsymmetrical sulfide
- Ohmori, Hidenobu,Maeda, Hatsuo,Konomoto, Kohichi,Sakai, Kiyoshi,Masui, Masaichiro
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p. 4473 - 4481
(2007/10/02)
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