- Phosphorylation Organocatalysts Highly Active by Design
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The activity of nucleophilic organocatalysts for alcohol/phenol phosphorylation was enhanced through attaching oligoether appendages to a benzyl substituent on imidazole- or aminopyridine-based active units, presumably because of stabilizing n-cation interactions of the ethereal oxygens with the positively charged aza-heterocycle in the catalytic intermediates, and was substantially higher than that of known benchmark catalysts for a range of substrates. Density functional theory calculations and the study of analogues having a lower potential for such stabilizing interactions support our hypothesis.
- Dobrovetsky, Roman,Fallek, Amit,Kramer, Maria,Portnoy, Moshe,Weiss-Shtofman, Mor
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- Dual utility of a single diphosphine-ruthenium complex: A precursor for new complexes and, a pre-catalyst for transfer-hydrogenation and Oppenauer oxidation
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The diphosphine-ruthenium complex, [Ru(dppbz)(CO)2Cl2] (dppbz = 1,2-bis(diphenylphosphino)benzene), where the two carbonyls are mutually cis and the two chlorides are trans, has been found to serve as an efficient precursor for the synthesis of new complexes. In [Ru(dppbz)(CO)2Cl2] one of the two carbonyls undergoes facile displacement by neutral monodentate ligands (L) to afford complexes of the type [Ru(dppbz)(CO)(L)Cl2] (L = acetonitrile, 4-picoline and dimethyl sulfoxide). Both the carbonyls in [Ru(dppbz)(CO)2Cl2] are displaced on reaction with another equivalent of dppbz to afford [Ru(dppbz)2Cl2]. The two carbonyls and the two chlorides in [Ru(dppbz)(CO)2Cl2] could be displaced together by chelating mono-anionic bidentate ligands, viz. anions derived from 8-hydroxyquinoline (Hq) and 2-picolinic acid (Hpic) via loss of a proton, to afford the mixed-tris complexes [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], respectively. The molecular structures of four selected complexes, viz. [Ru(dppbz)(CO)(dmso)Cl2], [Ru(dppbz)2Cl2], [Ru(dppbz)(q)2] and [Ru(dppbz)(pic)2], have been determined by X-ray crystallography. In dichloromethane solution, all the complexes show intense absorptions in the visible and ultraviolet regions. Cyclic voltammetry on the complexes shows redox responses within 0.71 to -1.24 V vs. SCE. [Ru(dppbz)(CO)2Cl2] has been found to serve as an excellent pre-catalyst for catalytic transfer-hydrogenation and Oppenauer oxidation.
- Mukherjee, Aparajita,Bhattacharya, Samaresh
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p. 15617 - 15631
(2021/05/19)
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- Heteroleptic 1,4-Diazabutadiene Complexes of Ruthenium: Synthesis, Characterization and Utilization in Catalytic Transfer Hydrogenation
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Reaction of [Ru(trpy)Cl3] with 1,4-diazabutadienes (p-RC6H4N=C(H)-(H)C=NC6H4R-p; R = OCH3, CH3, H and Cl; abbreviated as L-R) in refluxing ethanol in the presence of triethylamine has afforded a family of complexes, isolated as perchlorate salts, of type [Ru(trpy)(L-R)Cl]ClO4 [depicted as complexes 1 (R = OCH3), 2 (R = CH3), 3 (R = H) and 4 (R = Cl)]. Crystal structures of complexes 1, 2 and 4 have been determined, and structure of complex 3 has been optimized by DFT method. The 1,4-diazabutadiene ligand in each complex is bound to ruthenium as a N,N-donor forming five-membered chelate. Complexes 1–4 catalyze transfer hydrogenation of aryl aldehydes to the corresponding alcohols with high (ca. 106) TON. They are also found to catalyze transfer hydrogenation of aryl ketones to corresponding secondary alcohols, but with much less efficiency. Catalytic transfer hydrogenation of nitroarenes to the corresponding amines has also been achieved.
- Saha, Rumpa,Mukherjee, Aparajita,Bhattacharya, Samaresh
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p. 4539 - 4548
(2020/11/30)
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- Methanol as hydrogen source: Transfer hydrogenation of aromatic aldehydes with a rhodacycle
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A cyclometalated rhodium complex has been shown to perform highly selective and efficient reduction of aldehydes, deriving the hydrogen from methanol. With methanol as both the solvent and hydrogen donor under mild conditions and an open atmosphere, a wide range of aromatic aldehydes were reduced to the corresponding alcohols, without affecting other functional groups.
- Aboo, Ahmed H.,Bennett, Elliot L.,Deeprose, Mark,Robertson, Craig M.,Iggo, Jonathan A.,Xiao, Jianliang
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supporting information
p. 11805 - 11808
(2018/11/10)
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- Novel leucine ureido derivatives as aminopeptidase N inhibitors using click chemistry
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The over-expression of aminopeptidase N on diverse malignant cells is associated with the tumor angiogenesis and metastasis. In this report, one new series of leucine ureido derivatives containing the triazole moiety was designed, synthesized and evaluated as APN inhibitors. Among them, compound 13v showed the best APN inhibition with an IC50 value of 0.089 ± 0.007 μM, which was two orders of magnitude lower than that of bestatin (IC50 = 9.4 ± 0.5 μM). Compound 13v also showed dose-dependent anti-angiogenesis activities. Even at the lower concentration (10 μM), compound 13v presented similar anti-angiogenesis activity compared with bestatin at 100 μM in both the human umbilical vein endothelial cells (HUVECs) capillary tube formation assay and the rat thoracic aorta rings test. Moreover, compared with bestatin, 13v exhibited comparable, if not better in vivo anti-metastasis activity in a mouse H22 pulmonary metastasis model.
- Cao, Jiangying,Ma, Chunhua,Zang, Jie,Gao, Shuai,Gao, Qianwen,Kong, Xiujie,Yan, Yugang,Liang, Xuewu,Ding, Qin'ge,Zhao, Chunlong,Wang, Binghe,Xu, Wenfang,Zhang, Yingjie
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p. 3145 - 3157
(2018/06/01)
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- Aluminum Monohydride Catalyzed Selective Hydroboration of Carbonyl Compounds
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The well-defined aluminum monohydride compound [{(2,4,6-Me3-C6H2)NC(Me)}2(Me)(H)]AlH·(NMe2Et) (1) catalyzes hydroboration of a wide range of aldehydes and ketones under mild reaction conditions. Moreover, compound 1 displayed chemoselective hydroboration of aldehydes over ketones at rt.
- Jakhar, Vineet Kumar,Barman, Milan Kr.,Nembenna, Sharanappa
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supporting information
p. 4710 - 4713
(2016/09/28)
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- Ruthenium Catalyzed Selective Hydroboration of Carbonyl Compounds
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Using the [Ru(p-cymene)Cl2]2 (1) complex, catalytic hydroboration of aldehydes and ketones with pinacolborane under neat and mild conditions is reported. At rt, chemoselective hydroboration of aldehydes over the ketones is also attained. Mechanistic studies confirmed the immediate formation of monohydride bridged dinuclear complex [{(μ6-p-cymene)RuCl}2(μ-H-μ-Cl)] (1b) from the reaction of 1 with pinacolborane, which catalyzed the highly efficient hydroboration reactions. The catalytic cycle containing mononuclear Ru-H species and intramolecular 1,3-hydride transfer is postulated.
- Kaithal, Akash,Chatterjee, Basujit,Gunanathan, Chidambaram
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supporting information
p. 4790 - 4793
(2015/10/12)
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- Compounds for the treatment of metabolic disorders
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Compounds useful for the treatment of various metabolic disorders, such as insulin resistance syndrome, diabetes, hyperlipidemia, fatty liver disease, cachexia, obesity, atherosclerosis and arteriosclerosis, are disclosed.
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Page/Page column 93; 94; 99; 100
(2016/03/12)
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- FeCl3-catalyzed self-cleaving deprotection of methoxyphenylmethyl-protected alcohols
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4-Methoxyphenylmethyl ethers are widely utilized as alcohol protecting groups. FeCl3 effectively catalyzes the deprotection of methoxyphenylmethyl-type ethers in a self-cleaving manner to produce oligomeric derivatives and alcohols. Remarkably, the highly pure mother alcohols can be obtained without silica gel column chromatography by using the 2,4-dimethoxyphenylmethyl group as a protective group.
- Sawama, Yoshinari,Masuda, Masahiro,Asai, Shota,Goto, Ryota,Nagata, Saori,Nishimura, Shumma,Monguchi, Yasunari,Sajiki, Hironao
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supporting information
p. 434 - 437
(2015/03/03)
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- Synthesis and in vitro antibacterial activity of gemifloxacin derivatives containing a substituted benzyloxime moiety
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A series of novel gemifloxacin (GMFX) derivatives containing a substituted benzyloxime moiety with remarkable improvement in lipophilicity were synthesized. The target compounds evaluated for their in vitro antibacterial activity against representative strains. Our results reveal that most of the target compounds have considerable potency against all of the tested Gram-positive strains including MRSA and MRSE (MIC: 90: 1 μg/mL) is 8-fold more active than GMFX, and 2-fold more active than GMFX and moxifloxacin against MRSE clinical isolates (MIC90: 4 μg/mL). Crown Copyright
- Feng, Lianshun,Lv, Kai,Liu, Mingliang,Wang, Shuo,Zhao, Jing,You, Xuefu,Li, Sujie,Cao, Jue,Guo, Huiyuan
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p. 125 - 136
(2012/11/07)
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- Development of a novel benzyl mercaptan as a recyclable odorless substitute of hydrogen sulfide
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2,4,6-Trimethoxybenzyl mercaptan (4) was developed as an odorless substitute of hydrogen sulfide to afford β-mercapto carbonyl compounds in a Michael addition and to convert alkyl bromides into alkanethiols. Detrimethoxybenzylation of the Michael adducts prepared from 4 and α,β-unsaturated esters or ketones was facilely carried out by treatment with a solvent mixture of trifluoroacetic acid and toluene to give β-mercapto carbonyl compounds. Successive alkaline hydrolysis of 2,4,6-trimethoxybenzyl isothiouronium salt, which was obtained as a side product, regenerated 4 accompanying disulfide 8 in good yield. The disulfide 8 was also converted into 4 by reduction with LiAlH4. A similar protocol was applicable to the synthesis of alkanethiols using the S N2 reaction of alkyl bromides. Our method could be complementary to the classical method of using malodorous benzyl mercaptan as a nucleophile and Birch reduction for debenzylation. Georg Thieme Verlag Stuttgart.
- Matoba, Manabu,Kajimoto, Tetsuya,Node, Manabu
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p. 1930 - 1934
(2008/03/27)
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- On water and in air: Fast and highly chemoselective transfer hydrogenation of aldehydes with iridium catalysts
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(Chemical Equation Presented) Water as solvent: A fast, selective, and high-yielding transfer hydrogenation of a wide range of aldehydes is achieved using IrIII catalysts containing simple ethylene-diamine (en) ligands (see scheme; Ts = p-toluenesulfonyl, TOF = turnover frequency). This procedure is suitable for aldehydes with a wide range of functional groups.
- Wu, Xiaofeng,Liu, Jianke,Li, Xiaohong,Zanotti-Gerosa, Antonio,Hancock, Fred,Vinci, Daniele,Ruan, Jiwu,Xiao, Jianliang
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p. 6718 - 6722
(2007/10/03)
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- A scaleable synthesis of fiduxosin
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Fiduxosin (1) has been under development at Abbott Laboratories for the treatment of benign prostatic hyperplasia. A convergent strategy required methodologies for preparation of an enantiomerically pure 3,4-cis-disubstituted pyrrolidine and a 2,3,5-trisubstituted thienopyrazine in a regiospecific manner. A [3+2] cycloaddition of an enantiopure azomethine ylide followed by a diastereoselective crystallization was employed to prepare the benzopyranopyrrolidine in high diastereomeric and enantiomeric purity. Conditions for reduction of an O-aryl lactone susceptible to epimerization were developed, and cyclization of the alcohol/phenol to the ether was accomplished in high yield. The thienopyrazine was prepared by condensation of methyl thioglycolate and a regiospecifically prepared 2-bromo-3-cyano-5-phenylpyrazine. Conditions for effective halogen substitutive deamination to prepare regiospecific trisubstituted pyrazines will be described.
- Haight, Anthony R.,Bailey, Anne E.,Baker, William S.,Cain, Michael H.,Copp, Richard R.,Demattei, John A.,Ford, Kelley L.,Henry, Rodger F.,Hsu, Margaret C.,Keyes, Robert F.,King, Steven A.,McLaughlin, Maureen A.,Melcher, Laura M.,Nadler, William R.,Oliver, Patricia A.,Parekh, Shyamal I.,Patel, Hemant H.,Seif, Louis S.,Staeger, Mike A.,Wayne, Gregory S.,Wittenberger, Steven J.,Zhang, Weijiang
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supporting information
p. 897 - 902
(2013/09/03)
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- Compounds for the treatment of metabolic disorders
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Compounds useful for the treatment of various metabolic disorders, such as insulin resistance syndrome, diabetes, hyperlipidemia, fatty liver disease, cachexia, obesity, atherosclerosis and arteriosclerosis, are disclosed.
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- Synthesis and reactivity of benzylic sulfonium salts: Benzylation of phenol and thiophenol under near-neutral conditions
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A series of benzyldimethylsulfonium - and related hydrogensulfate salts have been synthesized from the ternary system ArCH2OH:H2SO4: Me2S or tetrahydrothiophene. The salts are generally stable crystalline solids, but anomalously high reactivity is observed for 9-(anthrylmethyl)dimethylsulfonium hydrogensulfate. Selected sulfonium salts have been used for the O- and S-benzylation of phenol and thiophenol, respectively, in a two phase system under near-neutral conditions. The benzylation of oximes and benzimidazole under basic conditions is also described.
- Forrester,Jones,Newton,Preston
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p. 2871 - 2884
(2007/10/03)
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- The cooperative effect of electrostatic and hydrophobic forces in the complexation of cationic molecules by a water-soluble resorcin[4]arene derivative
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A new water-soluble resorcin[4]arene derivative 4 was synthesized and the complexation of cationic guests in D2O was studied by 1H NMR spectroscopy. A 1:1 binding mode was elucidated by a Job's plot. The cooperative effect of electrostatic and hydrophobic interactions acts as a binding force for a strong complex formation with appropriate cationic guests in water. The thermodynamic parameters of complexation of guest I determined by a van't Hoff plot indicate that the complexation process is both enthalpically and entropically driven. (C) 2000 Elsevier Science Ltd.
- Park,Hong
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p. 8311 - 8315
(2007/10/03)
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- A facile cleavage of oxazolines to carbinols
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Treatment of oxazolines with chloromethyl methylether followed by diisobutylaluminium hydride leads to good yields of the carbinols.
- Meyers,Shimano
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p. 4893 - 4896
(2007/10/02)
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- Synthesis and Characterization of a Membrane-Spanning Porphinatoiron(II)
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A new tetraphenylporphinatoiron(II) having a couple of four amphiphilic chains on both sides of the porphyrin ring plane, 5,10,15,20-tetra(2',6'-di(20''-hydroxy-2'',2''-dimethylicosanoyloxy)-phenyl)porphinatiron, was synthesized as a model for membrane intrinsic proteins.It was well incorporated in the liposomal bilayer and characterized.The complex with 1-dodecylimidazole embedded in phospholipid bilayer formed an oxygen adduct in water at 25 deg C.
- Tsuchida, Eishun,Hasegawa, Etsuo,Komatsu, Teruyuki,Nakata, Taisaku,Nishide, Hiroyuki
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p. 389 - 392
(2007/10/02)
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- Structure-Reactivity Studies and Catalytic Effects in the Photosolvolysis of Methoxy-substituted Benzyl Alcohols
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The photosolvolysis of several methoxy-, dimethoxy-, and hydroxy-substituted benzyl alcohols has been studied in aqueous solution.The primary photochemical event is photodehydroxylation, to give a benzyl cation intermediate, which can be trapped by added external nucleophiles.The reaction is via the singlet excited state, based on observation of fluorescence quenching by hydronium ion in a complementary manner with acid catalysis of reaction observed for several derivatives.Solvent isotope effects on fluorescence efficiency and reaction for (7) and (8) provide additional support of singlet-state reactivity for these compounds.Dimethoxy-substituted alcohols are more reactive than monosubstituted compounds, with quantum yields of methanolysis of up to 0.31 for the most reactive compound, 2,6-dimethoxybenzyl alcohol (8).Using a kinetic argument, the quantum yields of the primary photodehydroxylation process has been estimated to be 1.0 +/- 0.1 for this compound.The results observed for the dimethoxy-substituted derivatives suggest the existence of additivity of substituent effects in these photodehydroxylation reactions.
- Wan, Peter,Chak, Becky
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p. 1751 - 1756
(2007/10/02)
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