- UV Light Generation and Challenging Photoreactions Enabled by Upconversion in Water
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Sensitized triplet-triplet annihilation (sTTA) is the most promising mechanism for pooling the energy of two visible photons, but its applications in solution were so far limited to organic solvents, with a current maximum of the excited-singlet state energy of 3.6 eV. By combining tailor-made iridium complexes with naphthalenes, we demonstrate blue-light driven upconversion in water with unprecedented singlet-state energies approaching 4 eV. The annihilators have outstanding excited-state reactivities enabling challenging photoreductions driven by sTTA. Specifically, we found that an aryl-bromide bond activation can be achieved with blue photons, and we obtained full conversion for the very energy-demanding decomposition of a persistent ammonium compound as typical water pollutant, not only with a cw laser but also with an LED light source. These results provide the first proof-of-concept for the usage of low-power light sources for challenging reactions employing blue-to-UV upconversion in water and pave the way for the further development of sustainable light-harvesting applications.
- Pfund, Bj?rn,Steffen, Debora M.,Schreier, Mirjam R.,Bertrams, Maria-Sophie,Ye, Chen,B?rjesson, Karl,Wenger, Oliver S.,Kerzig, Christoph
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supporting information
p. 10468 - 10476
(2020/07/27)
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- Asymmetric Hydrolytic and Aminolytic Kinetic Resolution of Racemic Epoxides using Recyclable Macrocyclic Chiral Cobalt(III) Salen Complexes
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New chiral macrocyclic cobalt(III) salen complexes were synthesized and used as catalyst for the asymmetric kinetic resolution (AKR) of terminal epoxides and glycidyl ethers with aromatic/aliphatic amines and water as nucleophiles. This is the first occasion where a Co(III) salen complex demonstrated its ability to catalyze AKR as well as hydrolytic kinetic resolution (HKR) reactions. Excellent enantiomeric excesses of the epoxides, the corresponding amino alcohols and diols (upto 99%) with quantitative yields were achieved by using the chiral Co(III) salen complexes in dichloromethane at room temperature. This protocol was further extended for the synthesis of two important drug molecules, i.e., (S)-propranolol and (R)-naftopidil. The catalytic system was also explored for the synthesis of chirally pure diols and chiral cyclic carbonates using carbon dioxide as a greener renewable C1 source. The catalyst was recycled for upto 5 catalytic cycles with retention of enantioselectivity. (Figure presented.).
- Tak, Rajkumar,Kumar, Manish,Menapara, Tusharkumar,Gupta, Naveen,Kureshy, Rukhsana I.,Khan, Noor-ul H.,Suresh
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supporting information
p. 3990 - 4001
(2017/11/22)
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- One-pot synthesis of aryloxypropanediols from glycerol: Towards valuable chemicals from renewable sources
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Glycerol offers an easy and green route for the synthesis of aryloxypropanediols of known pharmacological activity. Glycerol is selectively converted to aryloxypropanediols in a one-pot reaction, through in situ formed glycerol carbonate, under benign and solvent-free conditions. Catalyst and unreacted reagent can be recycled.
- Truscello, Ada M.,Gambarotti, Cristian,Lauria, Mirvana,Auricchio, Sergio,Leonardi, Gabriella,Shisodia, Suresh U.,Citterio, Attilio
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supporting information
p. 625 - 628
(2013/03/29)
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- Straightforward heterogeneous palladium catalyzed synthesis of aryl ethers and aryl amines via a solvent free aerobic and non-aerobic dehydrogenative arylation
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Aryl ethers have been prepared from cyclohexanone derivatives and various alcohols in the presence of a catalytic amount of palladium on charcoal. The formation of an enol ether followed by an aerobic or non-aerobic dehydrogenation reaction, seem to be the key steps of this transformation. In addition, this new method was also adapted for the synthesis of arylamines.
- Sutter, Marc,Sotto, Nicolas,Raoul, Yann,Metay, Estelle,Lemaire, Marc
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supporting information
p. 347 - 352
(2013/03/28)
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- Heterogeneous palladium-catalyzed synthesis of aromatic ethers by solvent-free dehydrogenative aromatization: Mechanism, scope, and limitations under aerobic and non-aerobic conditions
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Starting from cyclohexanone derivatives and alcohols, both non-aromatic precursors, aryl ethers could be synthesized in good yields and with good selectivities in the presence of a catalytic amount of Pd/C, in one step, without added solvent, in a reaction vessel open to air. For less reactive substrates, the addition of 1-octene in a closed system under non-aerobic conditions improved the conversion. In addition, the catalyst could be recycled several times with no decrease in the yield of the aryl ether. The process was also used with tetralone derivatives and polyols. Several reactions were performed to propose a mechanism for this transformation. The formation of an enol ether followed by a dehydrogenation reaction seem to be the key steps of this reaction. Aryl ethers were prepared in good yields and with good selectivities in a solvent-free and heterogeneous catalytic dehydrogenative alkylation of cyclohexanones with various alcohols. Three different complementary routes were used, and for the first time, non-aerobic, safe conditions could be used. Moreover, the catalyst could be recycled several times with no decrease in the yield of the aryl ether. Copyright
- Sutter, Marc,Lafon, Romain,Raoul, Yann,Metay, Estelle,Lemaire, Marc
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supporting information
p. 5902 - 5916
(2013/09/23)
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- An unusual (R)-selective epoxide hydrolase with high activity for facile preparation of enantiopure glycidyl ethers
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A novel epoxide hydrolase (BMEH) with unusual (R)-enantioselectivity and very high activity was cloned from Bacillus megaterium ECU1001. Highest enantioselectivities (E>200) were achieved in the bioresolution of ortho-substituted phenyl glycidyl ethers and para-nitrostyrene oxide. Worthy of note is that the substrate structure remarkably affected the enantioselectivities of the enzyme, as a reversed (S)-enantiopreference was unexpectedly observed for the ortho-nitrophenyl glycidyl ether. As a proof-of-concept, five enantiopure epoxides (>99% ee) were obtained in high yields, and a gram-scale preparation of (S)-ortho-methylphenyl glycidyl ether was then successfully performed within a few hours, indicating that BMEH is an attractive biocatalyst for the efficient preparation of optically active epoxides. Copyright
- Zhao, Jing,Chu, Yan-Yan,Li, Ai-Tao,Ju, Xin,Kong, Xu-Dong,Pan, Jiang,Tang, Yun,Xu, Jian-He
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p. 1510 - 1518
(2011/08/03)
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- Cyclic sulfites, key intermediates in synthesis of 1-alkylamino-3-aryloxy-2-propanols from glycidol
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A number of 3-aryloxypropanedioles were obtained by treating glycidol with phenols. The latter with thionyl chloride afforded 4-aryloxymethyl-1,3,2-dioxathiolane 2-oxides. These compounds were also obtained from 4-chloromethyl-1,3,2-dioxathiolane 2-oxides by substitution aryloxy group for chlorine. The cyclic sulfides synthesized are universal intermediates in the synthesis of chiral aryloxypropanolamines among which are known β-adrenoblockaders, cardiovascular drugs. From (S)-glycidol, (S)-alprenolol, (S)-propanolol, and (S)-thymolol were synthesized.
- Bredikhina,Savel'ev,Bredikhin
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p. 213 - 219
(2007/10/03)
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- Baker's yeast mediated stereoselective biotransformation of 1-acetoxy-3-aryloxypropan-2-ones
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A series of 1-acetoxy-3-aryloxypropan-2-ones 1a-m were synthesized and subjected to biotransformation by baker's yeast yielding optically active monoacetates 5 or ent-5 and/or diols 4 of moderate to excellent enantiomeric purity. The dependence of the reduction/hydrolysis ratio and stereoselectivity on the size and substitution pattern of the aromatic moiety in the substrate is also discussed.
- Egri, Gabriella,Kolbert, Attila,Balint, Jozsef,Fogassy, Elemer,Novak, Lajos,Poppe, Laszlo
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p. 271 - 283
(2007/10/03)
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- Quaternary amine containing ether or ester lipid derivatives and therapeutic compositions
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Quaternary amine-containing ether lipid analogs of the formula are disclosed. R1 represents a hydrophobic group and R2 represents the backbone of the molecule, with the quaternary amine being linked directly to the backbone. Pharmaceutical compositions including these compounds and methods of combating tumors with these compounds are disclosed. Also disclosed is a method of combating viral infections with both these compounds and ET-18-OMe and its analogs.
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- Asymmetric dihydroxylation of aryl allyl ethers
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Asymmetric dihydroxylation of substituted aryl allyl ethers is described. Para-substituents are shown to favor high enantioselectivity (89-95%ee), while ortho-groups have a deleterious effect (28-63%ee). Four medicinal agents were prepared: guaifenesin (expectorant), mephenesin (muscle relaxant), chlorphenesin (antifungal) and propanolol (β-blocker).
- Wang,Zhang,Sharpless
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p. 2267 - 2270
(2007/10/02)
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- Nucleophilic Addition to Cyclic 1,2-Sulfites
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Addition of heteroatom nucleophiles has been shown to attack at either the C5- or the S-atom sites in 4-(benzyloxymethyl)-1,3-dioxa-2-thiolane 2-oxide.No C4-reactivity was observed.The regioselectivity depended on the type of nucleophile.
- Carlsen, Per H.,Aase, Kristin J.
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p. 617 - 619
(2007/10/02)
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- Synthesis and biological activity of novel quaternary ammonium derivatives of alkylglycerols and potent inhibitors of protein kinase C
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Alyklglycerols such as rac-1-O-octadecyl-2-O-methylglycerophosphochocholine (Et-18-OMe) have shown an inhibitory effect on the metastasis and growth of various cancer cell lines. Alkyl phospholipids have been shown to accumulate at the surface in several cell lines, the selectivity of which is still not clearly understood. A consequence of this action may lead to the inhibition of cell membrane related protein kinase C (PKC). The goal of this research was to develop ether lipid inhibitors of PKC to augment antineoplastic activity. This led to the synthesis and in vitro testing of a series of novel quaternary ammonium derivatives of alkylglycerols. The biological testing of these analogues on PKC stimulated with rac-1-O-oleoyl-2-O-acetylglycerol showed several analogues with inhibition comparable to that of Et-18-OMe.
- Marasco Jr.,Piantadosi,Meyer,Morris-Natschke,Ishaq,Small,Daniel
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p. 985 - 992
(2007/10/02)
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- Formation of Optically Active Aryloxyacetaldehyde Cyanohydrin Acetates with the Aid of a Microorganism
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Microorganisms that hydrolyze the one enantiomer of dl-phenoxyacetaldehyde cyanohydrin acetate were screened, and Bacillus coagulans isolated from soil was found to be the best.This bacterium was applied to the asymmetric hydrolysis of other aryloxyacetaldehyde derivatives to give satisfactory results.The effect of adding dimethyl sulfoxide to the medium is also described.
- Ohta, Hiromichi,Miyamae, Yoshitaka,Tsuchihashi, Gen-ichi
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p. 215 - 222
(2007/10/02)
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- Crown Cation Complex Effects. 20. Syntheses and Cation Binding Properties of Carbon-Pivot Lariat Ethers
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In an effort devise synthetic cation binders that will mimic the behavior of naturally occuring ionophores such as valinomycin, we have prepared approximately 30 macrocyclic (crown) polyethers bearing flexible side chains attached to the macro ring at carbon.In many of these "carbon-pivot" compounds, the side chain contains one or more neutral donor groups that, if in a suitable geometrical arrangement, may provide additional solvation to the macro-ring-bound cation.Although such donors often enhanced the cation binding ability, overall, the increases in stability constants were modest.The physical resemblance and concept of "roping and tying" the cation suggest the name "lariat ethers".Syntheses of these molecules and binding by them of Na+ and K+ cations are reported and conclusions drawn about the structural requirements and cation binding efficacy of these materials.
- Dishong, Dennis M.,Diamond, Craig J.,Cinoman, Michael I.,Gokel, Geoge W.
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p. 586 - 593
(2007/10/02)
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