430430-71-0Relevant academic research and scientific papers
Transition-metal-free decarboxylative thiolation of stable aliphatic carboxylates
Xing, Wei-Long,Liu, De-Guang,Fu, Ming-Chen
, p. 4593 - 4597 (2021/02/03)
A transition-metal-free decarboxylative thiolation protocol is reported in which primary, secondary, tertiary (hetero)aryl acetates and α-CN substituted acetates undergo the decarboxylative thiolation smoothly, to deliver a variety of functionalized aryl alkyl sulfides in moderate to excellent yields. Aryl diselenides are also amenable substrates for construction of C-Se bonds under the simple and mild reaction conditions. Moreover, the protocol is successfully applied to the late-stage modification of pharmaceutical carboxylates with satisfactory chemoselectivity and functional-group compatibility. This journal is
Thiourea-Catalyzed C?F Bond Activation: Amination of Benzylic Fluorides
Houle, Camille,Savoie, Paul R.,Davies, Clotilde,Jardel, Damien,Champagne, Pier Alexandre,Bibal, Brigitte,Paquin, Jean-Fran?ois
, p. 10620 - 10625 (2020/07/24)
We describe the first thiourea-catalyzed C?F bond activation. The use of a thiourea catalyst and Ti(OiPr)4 as a fluoride scavenger allows the amination of benzylic fluorides to proceed in moderate to excellent yields. Preliminary results with S- and O-based nucleophiles are also presented. DFT calculations reveal the importance of hydrogen bonds between the catalyst and the fluorine atom of the substrate to lower the activation energy during the transition state.
Nanolayered cobalt-molybdenum sulphides (Co-Mo-S) catalyse borrowing hydrogen C-S bond formation reactions of thiols or H2S with alcohols
Corma, Avelino,Sorribes, Iván
, p. 3130 - 3142 (2019/03/13)
Nanolayered cobalt-molybdenum sulphide (Co-Mo-S) materials have been established as excellent catalysts for C-S bond construction. These catalysts allow for the preparation of a broad range of thioethers in good to excellent yields from structurally diverse thiols and readily available primary as well as secondary alcohols. Chemoselectivity in the presence of sensitive groups such as double bonds, nitriles, carboxylic esters and halogens has been demonstrated. It is also shown that the reaction takes place through a hydrogen-autotransfer (borrowing hydrogen) mechanism that involves Co-Mo-S-mediated dehydrogenation and hydrogenation reactions. A novel catalytic protocol based on the thioetherification of alcohols with hydrogen sulphide (H2S) to furnish symmetrical thioethers has also been developed using these earth-abundant metal-based sulphide catalysts.
Alkyl Sulfides as Promising Sulfur Sources: Metal-Free Synthesis of Aryl Alkyl Sulfides and Dialkyl Sulfides by Transalkylation of Simple Sulfides with Alkyl Halides
Liu, Ting,Qiu, Renhua,Zhu, Longzhi,Yin, Shuang-Feng,Au, Chak-Tong,Kambe, Nobuaki
supporting information, p. 3833 - 3837 (2018/12/05)
A site-selective metal-free dealkylative approach to synthesize aryl alkyl and symmetrical dialkyl sulfides has been developed. This procedure is convenient and has wide functional group tolerance giving rise to sulfides carrying various alkyl chains from simple alkyl sulfides and alkyl halides in good to excellent yields. This transalkylation proceeds by an ionic mechanism via sulfonium intermediates and it was proposed that dimethylacetamide (DMAC) may participate in part to promote the reaction.
Enabling nucleophilic substitution reactions of activated alkyl fluorides through hydrogen bonding
Champagne, Pier Alexandre,Pomarole, Julien,Therien, Marie-Eve,Benhassine, Yasmine,Beaulieu, Samuel,Legault, Claude Y.,Paquin, Jean-Francois
supporting information, p. 2210 - 2213 (2013/06/26)
It was discovered that the presence of water as a cosolvent enables the reaction of activated alkyl fluorides for bimolecular nucleophilic substitution reactions. DFT calculations show that activation proceeds through stabilization of the transition structure by a stronger F···H 2O interaction and diminishing C-F bond elongation, and not simple transition state electrostatic stabilization. Overall, the findings put forward a distinct strategy for C-F bond activation through H-bonding.
Fragmentation of anion radicals with elimination of aryloxy groups
Dneprovskii,Fedosov
, p. 1438 - 1443 (2007/10/03)
4-Vinylbenzyl phenyl ether, 4-phenylbenzyl phenyl ether, 1- and 2-naphthylmethyl phenyl ethers react with sodium thiophenolate under photochemical stimulation with replacement of the phenoxy group. The composition of reaction products and relation of reactivity to the structure of substrates is consistent with anion-radical mechanism. The corresponding methoxy and cyano derivatives do not undergo the reaction.
Equilibrium acidities of some sulfones and sulfoxides in tetrahydrofuran
Streitwieser, Andrew,Wang, George Peng,Bors, Daniel A.
, p. 10103 - 10112 (2007/10/03)
Ion pair acidities are reported in tetrahydrofuran (THF) solution for the lithium and cesium salts of several sulfones and one sulfoxide. These salts are shown to be monomeric in the THF solutions studied. Thermodynamic constants are reported for several salts. The results and some conductivity studies show that both the lithium and cesium salts are contact ion pairs in THF. Because of ion association the relative pKs are slightly lower for cesium salts and much lower for lithium salts than for the free ions in DMSO solution.
Potentiation of the cytotoxicity of chloroethylnitrosourea by O6-arylmethylguanines
Kohda,Terashima,Koyama,Watanabe,Mineura
, p. 424 - 430 (2007/10/03)
It was reported recently that monomeric O6-benzylguanine (1) acts as an alternative substrate for a DNA repair enzyme, O6-alkylguanine-DNA alkyltransferase (AGT), and that therefore pretreatment of cells with 1 induces depletion of AGT resulting in an enhanced cytotoxic response to alkylating antitumor agents. In order to study the interaction of O6-benzylguanine derivatives with AGT and to obtain greater AGT depletion, me synthesized the following O6-arylmethylguanine derivatives and related compounds: O6-(4-, 3- and 2-fluorobenzyl)guanines (2, 3, 4), O6-(4-,3- and 2-trifluoromethylbenzyl)guanines (5, 6, 7), O6-(4-, 3- and 2-pyridylmethyl)guanines (8, 9, 10), O6-(2- and 1-naphthylmethyl)guanines (11, 12), O6-biphenylmethylguanine (13), S and Se analogues of O6-benzylguanine (14, 15) and O6-phenylguanine (16). Ten of these are new compounds. All these compounds were tested for their potentiation of N'-[(4-amino-2-methyl-5-pyrimidinyl)methyl] (ACNU) cytotoxicity using HeLa S3 and C6-1 cells. Compounds 2, 3, 5, 8, 9, 11 and 13 were active, as was 1. Compounds 7 and 12, with a substituent at the a position of the benzyl group, and compound 10, the a-nitrogen analogue of 1, were almost completely devoid of potentiating activity. These results suggest that the a-position of the O6-benzyl group plays an important role in the interaction of O6-benzylguanines with AGT. Of the other compounds, 4 and 6 exhibited very weak activity and 14, 15 and 16 were inactive. Possible reasons for these differences in activity are discussed in relation to the biomimetic dealkylation rates of O6-benzylguanine derivatives and the chemical characteristics of their substituents.
