2051-49-2Relevant articles and documents
A Semisynthetic Approach to New Immunoadjuvant Candidates: Site-Selective Chemical Manipulation of Escherichia coli Monophosphoryl Lipid A
D'Alonzo, Daniele,Cipolletti, Manuela,Tarantino, Giulia,Ziaco, Marcello,Pieretti, Giuseppina,Iadonisi, Alfonso,Palumbo, Giovanni,Alfano, Alberto,Giuliano, Mariateresa,De Rosa, Mario,Schiraldi, Chiara,Cammarota, Marcella,Parrilli, Michelangelo,Bedini, Emiliano,Corsaro, Maria M.
, p. 11053 - 11063 (2016)
A semisynthetic approach to novel lipid A derivatives from Escherichia coli (E. coli) lipid A is reported. This methodology stands as an alternative to common approaches based exclusively on either total synthesis or extraction from bacterial sources. It relies upon the purification of the lipid A fraction from fed-batch fermentation of E. coli, followed by its structural modification through tailored, site-selective chemical reactions. In particular, modification of the lipid pattern and functionalization of the phosphate group as well as of the sole primary hydroxyl group were accomplished, highlighting the unusual reactivity of the molecule. Preliminary investigations of the immunostimulating activity of the new semisynthetic lipid A derivatives show that some of them stand out as promising, new immunoadjuvant candidates.
Ketonization of hexanoic acid to diesel-blendable 6-undecanone on the stable zirconia aerogel catalyst
Lee, Yunsu,Choi, Jae-Wook,Suh, Dong Jin,Ha, Jeong-Myeong,Lee, Chang-Ha
, p. 288 - 293 (2015)
The ketonization of hexanoic acid, which can be prepared by the fermentation of sugars, was performed in an effort to obtain the diesel-blendable high-carbon-number ketone 6-undecanone in this study. Based on observations of the leaching of highly active base catalysts, magnesium oxide and manganese oxide, the stable amphoteric solid catalyst zirconia was selected for the acid-rich reaction environment. A high-surface-area zirconia aerogel was prepared, which successfully ketonized hexanoic acid to 6-undecanone with high conversion, 72.3%, and high selectivity, 92.6%. The further optimization of the porous structures of zirconia led to possibly improved mass transfer with approximately 35 nm of pores, which improved the catalytic activity of zirconia.
One-pot electrochemical synthesis of acid anhydrides from alcohols
Kashparova,Papina,Kashparov,Zhukova, I. Yu.,Ilchibaeva,Kagan, E. Sh.
, p. 2733 - 2735 (2017/12/26)
One-pot indirect electrochemical oxidation of alcohols in the methylene chloride–aqueous solution of sodium hydrocarbonate two-phase system in the presence of potassium iodide, 4-acetylamino-2,2,6,6-tetramethylpiperidin-1-oxyl, and 2,6-lutidine results in
Zinc(0)/dimethylformamide-mediated synthesis of symmetrical carboxylic anhydrides from acid chlorides
Serieys, Audrey,Botuha, Candice,Chemla, Fabrice,Ferreira, Franck,Pérez-Luna, Alejandro
, p. 5322 - 5323 (2008/12/22)
The high yielding synthesis of symmetrical carboxylic anhydrides from acid chlorides mediated by zinc dust in the presence of dimethylformamide is presented. A mechanism involving the reductive insertion of zinc(0) into the C-Cl bond of a Vilsmeier-type iminium intermediate as the crucial step is also proposed.
Reaction of dicarbonates with carboxylic acids catalyzed by weak Lewis acids: General method for the synthesis of anhydrides and esters
Bartoli, Giuseppe,Bosco, Marcella,Carlone, Armando,Dalpozzo, Renato,Marcantoni, Enrico,Melchiorre, Paolo,Sambri, Letizia
, p. 3489 - 3496 (2008/09/19)
The reaction between carboxylic acids (RCOOH) and dialkyl dicarbonates [(R1OCO)2O], in the presence of a weak Lewis acid such as magnesium chloride and the corresponding alcohol (R1OH) as the solvent, leads to the esters RCOOR1 in excellent yields. The mechanism involves a double addition of the acid to the dicarbonate, affording a carboxylic anhydride [(RCO)2O], R1OH and carbon dioxide. The esters arise from the attack of the alcohols on the anhydrides. Exploiting the lesser reactivity of tert-butyl alcohol in comparison with other alcohols, a clean synthesis of both carboxylic anhydrides and esters has been set up. In the former reaction, an acid/Boc2O molecular ratio of 2:1 leads to the anhydride in good to excellent yields, depending on the stability of the resulting anhydride to the usual workup conditions. In the latter reaction, stoichiometric mixtures of the acid and Boc2O are allowed to react with a twofold excess of a primary alcohol, secondary alcohol or phenol (R 2OH) to give the corresponding esters (RCOOR2). Purification of the products is particularly easy since all byproducts are volatile or water soluble. A very easy chromatography is required only in the case of nonvolatile alcohols. A broad variety of sensitive functional groups is tolerated on both the acid and the alcohol, in particular a high chemoselectivity is observed. In fact, no transesterification processes occur with the acid-sensitive acetoxy group and methyl esters. Georg Thieme Verlag Stuttgart.
ZnCl2-mediated synthesis of carboxylic anhydrides using 2-acyl-4,5-dichloropyridazin-3(2H)-ones
Park, Yong-Dae,Kim, Jeum-Jong,Kim, Ho-Kyun,Cho, Su-Dong,Kang, Young-Jin,Park, Ki Hun,Lee, Sang-Gyeong,Yoon, Yong-Jin
, p. 371 - 378 (2007/10/03)
ZnCl2 is an efficient catalyst for synthesis of carboxylic acid anhydride from 2-acyl-4,5-dichloropyridazin-3(2H)-ones. Treatment of 2-acyl-4,5-dichloropyridazin-3(2H)-ones with ZnCl2 (0.5 equivalents) and air in refluxing dry THF or
A catalyst system for the reaction of carboxylic acids with aliphatic isocyanates
Gürtler,Danielmeier
, p. 2515 - 2521 (2007/10/03)
Catalysts have been found for the selective reaction of aliphatic isocyanates with carboxylic acids giving amides after carbon dioxide extrusion. Magnesium and calcium salts lead to a dramatic increase in reaction rates while improving the selectivity when sterically hindered isocyanates and/or carboxylic acids are used.
Cobalt(II)-Catalyzed Reaction of Aldehydes with Acetic Anhydride under an Oxygen Atmosphere: Scope and Mechanism
Bhatia, Beena,Punniyamurthy, T.,Iqbal, Javed
, p. 5518 - 5523 (2007/10/02)
The reaction of aldehydes with acetic anhydride in the presence of catalytic cobalt(II) chloride under an oxygen atmosphere at ambient temperature is dependent upon the reaction medium.Aliphatic aldehydes react in acetonitrile to give 1,2-diones whereas the aromatic aldehydes are acylated to yield the corresponding acylals.On the other hand, carboxylic acids are obtained from aliphatic and aromatic aldehydes by conducting the reaction in dichloroethane or benzene.Cobalt(II) chloride in acetonitrile catalyzes the conversion of aliphatic aldehydes to the correspondinganhydrides in the absence of acetic anhydride whereas aromatic aldehydes remain largely unaffected under these conditions.A preliminary mechanistic study in three different solvents (i.e. acetonitrile, dichloroethane, and DMF) has revealed that in acetonitrile and in the presence of acetic anhydride, aliphatic aldehydes behave differently than aromatic aldehydes.Some trapping experiments using methyl acrylate and stilbene have been conducted to demonstrate the occurence of an acyl cobalt and peroxyacyl cobalt intermediate during these reactions.
Hydroxy protection groups
-
, (2008/06/13)
The present invention concerns a method for preparing unprotected hydroxy compounds or acylated derivatives thereof by conversion of silyl alkyl-protected hydroxy compounds. The invention also relates to novel intermediates useful in the method and for other purposes.
PHASE MANAGED ORGANIC SYNTHESIS 2. A NEW POLYMER ASSISTED SYNTHESIS OF ACID ANHYDRIDES.
Fife, Wilmer K.,Zhang, Zhi-dong
, p. 4933 - 4936 (2007/10/02)
A solid-phase copolymer of 4-vinylpyridine is shown to be a highly effective reagent/catalyst for the synthesis of acid anhydrides from mixtures containing equimolar quantities of carboxylic acid and acid chlorides.The process may be carried out in batch or column mode.
