- Four- and Five-Coordinate Titanium(IV) Complexes Supported by the dpp-bian Ligand in ROP of L-Lactide
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A titanium(IV) alkoxido complex, (dpp-bian)Ti(OBn)2 (2), as well as alkoxido chlorido complexes (dpp-bian)TiCl(OCH2CH2OMe) (3) and (dpp-bian)TiCl2OBn (4), were synthesized from the titanium(IV) dichloride precursor [(dpp-bian)TiCl2]2 (1) by exchange with corresponding sodium salts (comps. 2 and 3) or by the alcoholysis with BnOH (comp. 4). The compounds 2–4 were fully characterized by elemental analysis, NMR or EPR, and IR spectroscopy. Molecular structures of the metal complexes in the solid state have been determined by single-crystal XRD analysis. Compounds 2–4 were tested as catalysts in the ROP of L-lactide in a toluene medium. Whereas complexes 2 and 3 produce cyclic PLAs with broad dispersities and unpredictable molecular weights, complex 4 acts as an efficient ROP catalyst which polymerizes the monomer in a highly controllable manner. It produces BnO-capped PLAs with narrow molecular weight distributions as well as linear dependence of Mns on monomer conversion.
- Morozov, Alexander G.,Martemyanova, Tatyana V.,Dodonov, Vladimir A.,Kazarina, Olga V.,Fedushkin, Igor L.
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Read Online
- NHC-CDI Betaine Adducts and Their Cationic Derivatives as Catalyst Precursors for Dichloromethane Valorization
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Zwitterionic adducts of N-heterocyclic carbene and carbodiimide (NHC-CDI) are an emerging class of organic compounds with promising properties for applications in various fields. Herein, we report the use of the ICyCDI(p-Tol) betaine adduct (1a) and its cationic derivatives2aand3aas catalyst precursors for the dichloromethane valorization via transformation into high added value products CH2Z2(Z = OR, SR or NR2). This process implies selective chloride substitution of dichloromethane by a range of nucleophiles Na+Z-(preformed or generatedin situfrom HZ and an inorganic base) to yield formaldehyde-derived acetals, dithioacetals, or aminals with full selectivity. The reactions are conducted in a multigram-scale under very mild conditions, using dichloromethane both as a reagent and solvent, and very low catalyst loading (0.01 mol %). The CH2Z2derivatives were isolated in quantitative yields after filtration and evaporation, which facilitates recycling the dichloromethane excess. Mechanistic studies for the synthesis of methylal CH2(OMe)2rule out organocatalysis as being responsible for the CH2transfer, and a phase-transfer catalysis mechanism is proposed instead. Furthermore, we observed that1aand2areact with NaOMe to form unusual isoureate ethers, which are the actual phase-transfer catalysts, with a strong preference for sodium over other alkali metal nucleophiles.
- Sánchez-Roa, David,Mosquera, Marta E. G.,Cámpora, Juan
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p. 16725 - 16735
(2021/11/18)
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- INHIBITORS OF THE PD-1/PD-L1 PROTEIN/PROTEIN INTERACTION
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The present invention provides novel compounds of formula (I) that are useful as inhibitors of the PD-1/PD-L1 protein/protein interaction.
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Page/Page column 30; 31
(2017/08/01)
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- Normal and abnormal heme biosynthesis. Part 7. Synthesis and metabolism of coproporphyrinogen-III analogues with acetate or butyrate side chains on rings C and D. Development of a modified model for the active site of coproporphyrinogen oxidase
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Analogues of coproporphyrinogen-III have been prepared with acetate or butyrate groups attached to the C and D pyrrolic subunits. The corresponding porphyrin methyl esters were synthesized by first generating a,c-biladienes by reacting a dipyrrylmethane with pyrrole aldehydes in the presence of HBr. Cyclization with copper(II) chloride in DMF, followed by demetalation with 15% H2SO4-TFA and reesterification, gave the required porphyrins in excellent yields. Hydrolysis with 25% hydrochloric acid and reduction with sodium-amalgam gave novel diacetate and dibutyrate porphyrinogens 9. Diacetate 9a was incubated with chicken red cell hemolysates (CRH), but gave complex results due to the combined action of two of the enzymes present in these preparations. Separation of uroporphyrinogen decarboxylase (URO-D) from coproporphyrinogen oxidase (CPO) allowed the effects of both enzymes on the diacetate substrate to be assessed. Porphyrinogen 9a proved to be a relatively poor substrate for CPO compared to the natural substrate coproporphyrinogen-III, and only the A ring propionate moiety was processed to a significant extent. Similar results were obtained for incubations of 9a with purified human recombinant CPO. Diacetate 9a was also a substrate for URO-D and a porphyrinogen monoacetate was the major product in this case; however, some conversion of a second acetate unit was also evident. The dibutyrate porphyrinogen 9b was only recognized by the enzyme CPO, but proved to be a modest substrate for incubations with CRH. However, 9b was an excellent substrate for purified human recombinant CPO. The major product for these incubations was a monovinylporphyrinogen, but some divinyl product was also generated in incubations using purified recombinant human CPO. The incubation products were converted into the corresponding porphyrin methyl esters, and these were characterized by proton NMR spectroscopy and mass spectrometry. The results extend our understanding of substrate recognition and catalysis for this intriguing enzyme and have allowed us to extend the active site model for CPO. In addition, the competitive action of both URO-D and CPO on the same diacetate porphyrinogen substrate provides additional perspectives on the potential existence of abnormal pathways for heme biosynthesis.
- Lash, Timothy D.,Lamm, Teresa R.,Schaber, J. Andy,Chung, Wen-Hsiang,Johnson, Eric K.,Jones, Marjorie A.
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experimental part
p. 1492 - 1504
(2011/04/12)
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- Solubility of sodium sulfide in alcohols
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The solubility of sodium sulfide in methanol, ethanol, 2-propanol, 2-methyl-1-propanol, and benzyl alcohol and the acid-base interaction of these compounds have been determined at (20 and 35) °C. The reactions result in the formation of sodium alkoxide and hydrosulfide. The reported values on the solubility of sodium sulfide in alcohols differ essentially from the data described in the literature.
- Kurzin, Alexander V.,Evdokimov, Andrey N.,Golikova, Valerija S.,Pavlova, Olesja S.
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experimental part
p. 4080 - 4081
(2011/05/28)
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- IMIDATE COMPOUND AND USE THEREOF FOR PEST CONTROL
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There is provided a compound having an excellent controlling effect on arthropod pests represented by the formula (I-1): wherein Z represents an optionally substituted carbocyclic group or an optionally substituted heterocyclic group; G represents a -A1-R1
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Page/Page column 222-223
(2009/03/07)
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- Synthesis of new 2-phosphono-α-d-glycoside derivatives by stereoselective oxa-Michael addition to a d-galacto derived enone
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The synthesis of new 2-phosphono-α-d-glycoside derivatives by stereoselective oxa-Michael addition to an enone derived from d-galactal and containing a phosphonate group is described. Retro-Michael reactions were prevented by tandem acetylation to trap the unstable enolic intermediates. The stereochemistry of the addition products was established by NOESY experiments and explained with molecular mechanics (MM) and density functional theory (DFT) calculations.
- Leonelli, Francesca,Capuzzi, Marinella,Bodo, Enrico,Passacantilli, Pietro,Piancatelli, Giovanni
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p. 1133 - 1141
(2008/09/21)
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- GLYCOSIDASE INHIBITORS AND METHODS OF SYNTHESIZING SAME
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The compounds of the present invention relate to chain-extended and chain-modified analogues of salacinol, including embodiments where the sulfate moiety has been substituted with a carboxylate or phosphate moiety. In other embodiments the sulfate moiety has been shifted by one carbon atom in the zwitterionic structure. In another embodiment the polyhydroxylated side chain may be replaced with a lipophilic alkyl chain and a suitable counterion. The invention also encompasses methods for synthesizing the salacinol analogues and using the analogues for enzyme inhibition applications.
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Page/Page column 18
(2010/11/28)
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- Processes for the preparation of 16beta-alkoxy, 17alpha-hydroxy steroids and steroidal 16beta, 17alpha-diols from 16alpha, 17alpha-epoxy steroids
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The present invention provides processes for the preparation of 16β-alkoxy, 17α-hydroxy steroids via the reaction of a 16α,17α-epoxy steroid with an appropriate alcohol in the presence of base. The present invention also provides processes for the preparation of 16β-alkoxy, 17α-hydroxy steroids.
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Page/Page column 7
(2008/06/13)
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- CHEMICAL COMPOUNDS
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Quinazoline derivatives of formula (I); for use in the treatment of proliferative diseases such as cancer and in the preparation of medicaments for use in the treatment of proliferative diseases, and to processes for their preparation, as well as pharmaceutical compositions containing them as active ingredient.
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- Porphyrins with Exocyclic Rings. Part 5. Synthesis of a Naphthoporphyrin.
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Condensation of 2-acetyl-1-tetralone with diethyl aminomalonate in refluxing acetic acid gave a dihydronaphthopyrrole 9a in excellent yield.Transesterification with benzyl alcohol gave the corresponding benzyl ester 9b and subsequent regioselective oxidation with lead tetraacetate afforded the acetoxymethyl derivative 13.Pyrrole 13 condensed with the α-unsubstituted pyrrole 14 to give the asymmetrical dipyrrylmethane 15 and hydrogenolysis over 10percent palladium-charcoal yielded the related dicarboxylic acid 16.Acid catalyzed condensation of 16 with dipyrrylmethane dialdehyde 18 gave the dihydronaphthoporphyrin 17 in 44percent yield.Alternatively, 17 condensed with two equivalents of pyrrole aldehyde 19 in the presence of HBr to give the a,c-biladiene 20 and cyclization with CuCl2 in DMF, followed by demetallation with 10percent H2SO4 in TFA, afforded 17 in 37percent yield.Dehydrogenation of 17 with DDQ in refluxing toluene gave 8, the first example of a naphthoporphyrin, in 76percent yield.Porphyrin 8 exhibited an unusual electronic spectrum and this may have value in the characterization of sedimentary porphyrins.
- Lash, Timothy D.,Denny, Carl P.
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- Regioselective synthesis of 9-substituted purine acyclonucleoside derivatives
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A process for preparing 9-substituted guanine-containing acyclonucleosides comprising selective alkylation at the 9-position of the purine by utilizing a blocking group at the 6-position.
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- REACTION OF 6H-6-OXO--3(5)-HALOGENOANTHRAISOXAZOLES WITH INORGANIC NUCLEOPHILES
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The reaction of 6H-6-oxo-3(5)-halogenoanthraisoxazoles with sodium azide in DMFA and also the potassium fluoride in acetonitrile in the presence of crown ethers leads to nucleophilic substitution of the halogen by the azide and fluoride ion respectively.
- Gornostaev, L. M.,Zeibert, G. F.
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p. 1192 - 1194
(2007/10/02)
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