- Method for synthesizing 1,3-dihydroxyacetone through indirect oxidation of glycerol
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The invention relates to a method for synthesizing 1,3-dihydroxyacetone through indirect oxidation of glycerol, the method comprises the following steps: carrying out an acetalation reaction, to be more specific, an organic solvent is used as a water-carrying agent, glycerol and benzaldehyde are subjected to acetalation reaction under the action of a solid acid catalyst to obtain 2-phenyl-5-hydroxy-1,3-dioxane (HPD); oxidizing reaction, to be more specific, in an organic solvent, the 2-phenyl-5-hydroxy-1,3-dioxane (HPD) is oxidized into 2-phenyl-5-carbonyl-1,3-dioxane (PDO) by an oxidizing agent under the action of a liquid catalyst and auxiliary agent sodium bromide; hydrolysis reaction, to be more specific, the 2-phenyl-5-carbonyl-1,3-dioxane (PDO) is subjected to hydrolysis reaction under the action of a liquid acid catalyst to obtain a target product. The synthetic process route takes the glycerol as a raw material, the selectivity and the yield are higher than that of the direct oxidation method, the target product is simple in separation, the purity of the product is up to 99%, and industrial production is facilitated.
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Paragraph 0025; 0026; 0029; 0031; 0033; 0035; 0037; 0039
(2019/04/18)
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- Stereocontrol by quaternary centres: A stereoselective synthesis of (-)-luminacin D
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Very high diastereoselectivity can be achieved by 1,3-chelation-controlled allylation of aldehydes that possess a non-chelating α-ether substituent, even if the α-position is a quaternary centre and/or a spiro-epoxide. This reaction was used as a key step in an enantioselective synthesis of the angiogenesis inhibitor luminacin D.
- Bartlett, Nathan,Gross, Leona,Peron, Florent,Asby, Daniel J.,Selby, Matthew D.,Tavassoli, Ali,Linclau, Bruno
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supporting information
p. 3306 - 3310
(2014/04/03)
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- Magnetic Polystyrene Nanosphere Immobilized TEMPO: A Readily Prepared, Highly Reactive and Recyclable Polymer Catalyst in the Selective Oxidation of Alcohols
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The 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical immobilized on the magnetic polystyrene nanospheres (MPNs) was used as a recyclable catalyst in the oxidation of various alcohols. The new and simply prepared heterogeneous TEMPO/MPNs exhibits both similar versatility and efficiency to homogeneous TEMPO under basic Montanari conditions. The excellent stability of the MPNs enables the TEMPO/MPNs to be recycled more than 20times without significant leaching of immobilized TEMPO radicals or degradation of Fe3O4 nanoparticles. Moreover, the magnetic response ensures the rapid separation and quantitative recycling of TEMPO/MPNs by simple magnetic decantation.
- Zheng, Zhi,Wang, Jianli,Zhang, Miao,Xu, Lixin,Ji, Jianbing
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p. 307 - 312
(2013/03/13)
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- Relative tendency of carbonyl compounds to form enamines
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Equilibria between carbonyl compounds and their enamines (from O-TBDPS-derived prolinol) have been examined by NMR spectroscopy in DMSO-d 6. By comparing the exchange reactions between pairs (enamine A + carbonyl B → carbonyl A + enamine B), a quite general scale of the tendency of carbonyl groups to form enamines has been established. Aldehydes quickly give enamines that are relatively more stable than those of ketones, but there are exceptions to this expected rule; for example, 1,3-dihydroxyacetone acetals or 3,5-dioxacyclohexanones (2-phenyl-1,3-dioxan-5-one and 2,2-dimethyl-1,3- dioxan-5-one) show a greater tendency to afford enamines than many α-substituted aldehydes.
- Sanchez, Dani,Bastida, David,Bures, Jordi,Isart, Carles,Pineda, Oriol,Vilarrasa, Jaume
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supporting information; experimental part
p. 536 - 539
(2012/03/26)
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- Conformationally constrained NR2B selective NMDA receptor antagonists derived from ifenprodil: Synthesis and biological evaluation of tetrahydro-3-benzazepine-1,7-diols
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NR2B selective NMDA receptor antagonists with tetrahydro-3-benzazepine-1,7- diol scaffold have been designed by formal cleavage and reconstitution of the piperidine ring of the lead compound ifenprodil (1). The secondary amine 10 represents the central bu
- Tewes, Bastian,Frehland, Bastian,Schepmann, Dirk,Schmidtke, Kai-Uwe,Winckler, Thomas,Wünsch, Bernhard
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supporting information; experimental part
p. 8005 - 8015
(2011/02/23)
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- Cyclic hexapeptides having antibiotic activity
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This invention relates to new polypeptide compound represented by general formula (I), wherein R1, R2, R3, R4, R5 and R6 are as defined in the description or a salt thereof which has antimicrobial activities (especially, antifungal activities), inhibitory activity on β-1,3-glucan synthase, to process for preparation thereof, to a pharmaceutical composition comprising the same, and to a method for prophylactic and/or therapeutic treatment of infectious diseases including Pneumocystis carinii infection (e.g. Pneumocystis carinii pneumonia) in a human being or an animal.
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- A method for the selective hydrolysis of ketone hydrazones in the presence of acetals
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Dimethylhydrazones and RAMP-hydrazones containing acetal or olefin groups were hydrolysed selectively to form the corresponding ketones, by treatment with ammonium dihydrogen phosphate buffer solutions.
- Ulven,Carlsen
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p. 3971 - 3972
(2007/10/03)
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- Stereoselective synthesis of substituted 5-hydroxy-1,3-dioxanes
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A series of 5-hydroxy-1,3-dioxanes has been synthesized using a practical three-step strategy beginning with acetal/ketal formation of tris(hydroxymethyl)aminomethane followed by oxidative cleavage of the amino alcohol. After the ketone was revealed, stereoselective reduction with common hydride reagents, LiAlH4 for the trans isomers and L-Selectride for the cis analogues, gave the target compounds in high yield.
- Forbes, David C.,Ene, Doina G.,Doyle, Michael P.
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p. 879 - 882
(2007/10/03)
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- 1,3-Dioxan-5-ones: synthesis, deprotonation, and reactions of their lithium enolates
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A general synthetic route to 2-alkyl- and 2,2-dialkyl-1,3-dioxan-5-ones, using tris(hydroxymethyl)nitromethane as the starting material, is described.Deprotonation of these compounds was studied.It was established that these dioxanones could be deprotonated with LDA; however, the reduction of the carbonyl group via a hydride transfer from LDA, giving the corresponding dioxanols, often competed with deprotonation.The reduction could be minimized by using Corey's internal quench procedure to form silyl enol ethers and was less pronounced in 2,2-dialkyldioxanones (ketals) than in 2-alkyldioxanones (acetals).Self-aldol products were observed when dioxanone lithium enolates were quenched with H2O.Addition reactions of lithium enolates of dioxanones to aldehydes were threo-selective as predicted by the Zimmerman-Traxler model.Dioxanones having two different alkyl groups at the 2-position were deprotonated enantioselectively by chiral lithium amide bases with enantiomeric excess (ee) of up to 70percent. - Key words: 1,3-dioxan-5-ones, enantioselective deprotonation, chiral lithium amides.
- Majewski, Marek,Gleave, D. Mark,Nowak, Pawel
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p. 1616 - 1626
(2007/10/02)
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- Origin of the "β-oxygen effect" in the Barton deoxygenation reaction
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Photolysis of O-neopentyl S-tributylstannyl dithiocarbonate with hexaphenyl distannane, and 4-methoxyacetophenone as sensitizer, results in crossover of the stannyl groups. The reaction of O-octyl O′-(2-butoxyethyl) thiocarbonate with tributyltin deuteride or tris(trimethylsilyl)silane and a radical initiator shows no significant preference for the cleavage of either C-O bond. Intermolecular competitions between O-octyl O′-phenyl thiocarbonate and O-(2-butoxyethyl) O′-phenyl thiocarbonate for a deficiency of stannane or silane also indicated no significant preference for reaction of the β-oxygen-substituted substrate, leading to the conclusion that in conformationally unrestricted systems there is no significant β-oxygen effect in the Barton deoxygenation reaction. Competition experiments between the cis- and trans-O-(4-phenylcyclohexyl) S-methyl dithiocarbonates and the cis- and trans-O-(2-phenyl1,3-dioxan-5-yl) S-methyl dithiocarbonates for reaction with tributylstannane reveal that in every case the heterocyclic system is more reactive. The cis-isomers of 4-phenylcyclohexyl S-methyl dithiocarbonate and O-(2-phenyl-1,3-dioxan-5-yl) 5-methyl dithiocarbonate, with their axial xanthates, are more reactive than the corresponding transisomers. Molecular mechanics calculations suggest that the greater reactivity of the cis-series with respect to the trans is due to the greater relief of strain on fragmentation.
- Crich, David,Beckwith, Athelstan L. J.,Chen, Chen,Yao, Qingwei,Davison, Ian G. E.,Longmore, Robert W.,De Parrodi, Cecilia Anaya,Quintero-Cortes, Leticia,Sandoval-Ramirez, Jésus
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p. 8757 - 8768
(2007/10/02)
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- Secondary deuterium isotope effects on both rate and product determining steps in the thermolysis of 4-methylene-1-pyrazoline
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The secondary deuterium kinetic isotope effect in the thermolysis of 4-methylene-1-pyrazoline and four of its deuterated isomers has been studied.The value of δΔG*/n is 142 cal mol-1 if it is a single C-N cleavage process or 71 cal mol-1 if it is a concerted rupture of two C-N bonds.The product distributions can only be rationalized in terms of a mechanism involving a rate determining C-N bond rupture to form a diazenyl diradical intermediate which then can close to methylenecyclopropanes by three possible modes.This requires a secondary isotope effect in the product determining step of 1.33 +/- 0.05, for the rotation of CH2 (CD2) out of the plane of the allylic radical in the intermediate.
- Chang, Moon Ho,Crawford, Robert J.
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p. 2556 - 2568
(2007/10/02)
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