115750-83-9Relevant academic research and scientific papers
An efficient procedure for the synthesis of ortho-trialkylsilylaryl triflates: Easy access to precursors of functionalized arynes
Pena, Diego,Cobas, Agustin,Perez, Dolores,Guitian, Enrique
, p. 1454 - 1458 (2002)
o-Trialkylsilylaryl triflates which are useful aryne precursors are prepared from o-bromophenols by an efficient, one-pot procedure involving O-silylation, metal-halogen exchange, O- to C-silyl migration, and entrapment of the phenoxide with triflic anhydride.
Tuning the cytotoxicity of ruthenium(ii) para-cymene complexes by mono-substitution at a triphenylphosphine/phenoxydiphenylphosphine ligand
Biancalana, Lorenzo,Zacchini, Stefano,Ferri, Nicola,Lupo, Maria Giovanna,Pampaloni, Guido,Marchetti, Fabio
, p. 16589 - 16604 (2017/12/15)
The new complexes [RuCl2(η6-p-cymene)(κP-Ph2PR)] [R = 4-C6H4OSiMe2tBu, 1; R = 4-C6H4Br, 2; R = OC(O)CHCl2, 3; R = OPh, 4; R = O(2-C6H4SiMe2tBu), 5] and [Ru(C2O4)(η6-p-cymene){κP-Ph2PO(2-C6H4(SiMe2tBu))}], 6, were obtained in 83-98% yield from Ru(ii) arene precursors by three different synthetic strategies. The unprecedented phosphine Ph2P(O(2-C6H4SiMe2tBu)) was synthesized in 86% yield from 2-C6H4Br(OSiMe2tBu) and Ph2PCl, via intramolecular oxygen to carbon 1,3 migration of the silyl group (retro-Brook rearrangement). All the complexes were fully characterized by analytical and spectroscopic methods, and by single crystal X-ray diffraction in the cases of 3, 4, 5 and 6. Complexes 1-6 and the model compounds [RuCl2(η6-p-cymene)(κP-PPh3)] (Ru-PPh3) and [Ru(C2O4)(η6-p-cymene)(κP-PPh3)] (Ru-PPh3-O) underwent slow degradation in chloroform solutions upon air contact; the mixed valence complex [(η6-p-cymene)Ru(μ-Cl)3RuCl2(κP-PPh3)], 7, was isolated from a solution of Ru-PPh3 in CHCl3, and X-ray identified. The antiproliferative activity of 1-6 and Ru-PPh3, Ru-PPh3-O and [RuCl2(η6-p-cymene)(κP-PTA)] (RAPTA-C) was assessed towards the triple-negative breast cancer cell line MDA-MB-231, the ovarian carcinoma cell line A2780 and human skin fibroblasts (HSF). Complexes 1, 2, 5 and 6 displayed IC50 values significantly lower than that of cisplatin, with 2 providing a more potent cytotoxic effect on MDA-MB-231 and A2780 cancer cells compared to the noncancerous cell line (HSF). The stability of all complexes in DMSO/water solution was elucidated by NMR and conductivity measurements, and in particular 35Cl NMR spectroscopy was helpful to check the possible chloride dissociation. The stability studies suggest that the cytotoxic activity in vitro of the compounds is mainly ascribable to Ru(ii) species still bound to the phosphorus ligand.
Titania-promoted carboxylic acid alkylations of alkenes and cascade addition-cyclizations
Manley, David W.,McBurney, Roy T.,Miller, Phillip,Walton, John C.,Mills, Andrew,O'Rourke, Christopher
, p. 1386 - 1398 (2014/03/21)
Photochemical reactions employing TiO2 and carboxylic acids under dry anaerobic conditions led to several types of C-C bond-forming processes with electron-deficient alkenes. The efficiency of alkylation varied appreciably with substituents in the carboxylic acids. The reactions of aryloxyacetic acids with maleimides resulted in a cascade process in which a pyrrolochromene derivative accompanied the alkylated succinimide. The selectivity for one or other of these products could be tuned to some extent by employing the photoredox catalyst under different conditions. Aryloxyacetic acids adapted for intramolecular ring closures by inclusion of 2-alkenyl, 2-aryl, or 2-oximinyl functionality reacted rather poorly. Profiles of reactant consumption and product formation for these systems were obtained by an in situ NMR monitoring technique. An array of different catalyst forms were tested for efficiency and ease of use. The proposed mechanism, involving hole capture at the TiO2 surface by the carboxylates followed by CO2 loss, was supported by EPR spectroscopic evidence of the intermediates. Deuterium labeling indicated that the titania likely donates protons from surface hydroxyl groups as well as supplying electrons and holes, thus acting as both a catalyst and a reaction partner.
Rhodium-catalyzed carbon-silicon bond activation for synthesis of benzosilole derivatives
Onoe, Masahiro,Baba, Katsuaki,Kim, Yoonjoo,Kita, Yusuke,Tobisu, Mamoru,Chatani, Naoto
supporting information, p. 19477 - 19488 (2013/02/21)
A rhodium-catalyzed coupling reaction of 2-trimethylsilylphenylboronic acid with internal alkynes is developed for the synthesis of 2,3-disubstituted benzosilole derivatives. A range of functional groups, encompassing ketones, esters, amines, aryl bromides, and heteroarenes, are compatible, which provides rapid access to diverse benzosiloles. Sequential 2-fold coupling enables modular synthesis of asymmetrically substituted 1,5-dihydro-1,5-disila-s-indacene, a π-extended molecule of interest in organic electronics. In terms of the mechanism, the reaction involves cleavage of a C(alkyl)-Si bond in a trialkylsilyl group, which normally requires extremely harsh conditions for activation. Mechanistic studies, including effects of substituents, reveal that C-Si bond cleavage does not proceed through a hypercoordinated silicon species, but rather through a rhodium-mediated activation process. The potential use of the reaction in catalytic asymmetric synthesis of Si-chiral benzosiloles is also demonstrated.
RENIN INHIBITORS
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Page/Page column 136, (2008/06/13)
Disclosed are compounds according to Formula (I): wherein the variables are defined herein. Such compounds are can bind aspartic proteases to inhibit their activity. They are useful in the treatment or amelioration of diseases associated with aspartic pro
PIPERIDINE AND MORPHOLINE RENIN INHIBITORS
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Page/Page column 152, (2008/06/13)
Described are compounds which are orally active and bind to renin to inhibit its activity. They are useful in the treatment or amelioration of diseases associated with renin activity. Also described are methods of use of these compounds for treating or ameliorating a renin mediated disorder in a subject.
Stereoselective ring-opening polymerization of a racemic lactide by using achiral salen- and homosalen-aluminum complexes
Nomura, Nobuyoshi,Ishii, Ryohei,Yamamoto, Yoshihiko,Kondo, Tadao
, p. 4433 - 4451 (2008/02/09)
Highly isotactic polylactide or poly(lactic acid) is synthesized in a ring-opening polymerization (ROP) of racemic lactide with achiral salen- and homosalen-aluminum complexes (salenH2 = N,N′-bis(salicylidene) ethylene-1,2-diamine; homosalenH2 = N,N′-bis(salicylidene) trimethylene-1,3-diamine). A systematic exploration of ligands demonstrates the importance of the steric influence of the Schiff base moiety on the degree of isotacticity and the backbone for high activity. The complexes prepared in situ are pure enough to apply to the polymerizations without purification. The crystal structures of the key complexes are elucidated by X-ray diffraction, which confirms that they are chiral. However. analysis of the 1H and 13C NMR spec tra unambiguously demonstrates that their conformations are so flexible that the chiral environment of the complexes cannot be maintained in solution at 25°C and that the complexes are achiral under the polymerization conditions. The flexibility of the back-bone in the propagation steps is also documented. Hence, the isotacticity of the polymer occurs due to a chain-end control mechanism. The highest reactivity in the present system is obtained with the homosalen ligand with 2.2-dimethyl substituents in the backbone (ArCH=NCH2CMe2CH2N=CHAr), whereas tBuMe2Si substituents at the 3-positions of the salicylidene moieties lead to the highest selectivity (Pmeso,= 0.98; T m = 210°C). The ratio of the rate constants in the ROPs of racemic lactide and L-lactide is found to correlate with the stereoselectivity in the present system. The complex can be utilized in bulk polymerization, which is the most attractive in industry, although with some loss of stereoselectivity at high temperature, and the afforded polymer shows a higher melting temperature (Pmeso = 0.92, Tm up to 189°C) than that of homochiral poly(L-lactide) (Tm = 162-180°C). The "livingness" of the bulk polymerization at 130°C is maintained even at a high conversion (97-98%) and for an extended polymerization time (1-2 h).
Synthesis of Aryloxy Analogues of Arachidonic Acid via Wittig and Palladium Catalysed Cross-coupling Reactions
Buckle, Derek R.,Fenwick, Ashley E.,Outred, D. James,Rockell, Caroline J. M.
, p. 3144 - 3177 (2007/10/02)
The synthesis of o- and p-phenoxy analogues of arachidonic acid is described.In particular, the Wittig olefination reaction of hydroxy and alkyloxy benzaldehydes has been investigated and the products shown to be highly dependent on the solvent used.E/Z isomer control was difficult to achieve in most cases, although there was a tendency towards Z-isomer formation in dimethyl sulphoxide compared to tetrahydrofuran, particularly for the phenolic compounds.Specific Z-isomer formation was achieved by the partial reduction of alkynes derived from appropriately protected bromophenols via Heck or palladium catalysed cross-coupling reactions.
