نتایج جستجو برای: anhydrides
تعداد نتایج: 2251 فیلتر نتایج به سال:
Efficient kinetic resolution processes continue to play a critical role in asymmetric synthesis.1 Using two chiral reagents to effect two parallel running enantioselective resolution reactions, Vedejs and co-workers demonstrated that, through minimizing a buildup of the less reactive enantiomer by simultaneously consuming both enantiomers of the racemic starting material, the two resolution rea...
Water-soluble metal working fluids are used for processing of aluminum alloy materials. This short article describes properties of new additives in water-soluble metal working fluids for aluminum alloy materials. Many half esters or diesters were prepared from the reactions of higher alcohols with acid anhydrides. Interestingly, diesters of PTMG (tetrahydrofuran oligomer, MW = 650 and 1000) and...
During the last few years it was observed that anhydrides of carboxylic and phosphoric acids appear as intermediates in metabolism. For one of these, acetyl phosphate, a method of determination had been worked out (I), based on a differential precipitation of calcium acetyl and inorganic phosphate with subsequent phosphate determination in the separate fractions. Such a procedure, founded on a ...
In the crystal structure of 2,3-di-methyl-maleic anhydride, C6H6O3, the closest non-bonding inter-molecular distances, between the carbonyl C and O atoms of neighboring mol-ecules, were measured as 2.9054 (11) and 3.0509 (11) Å, which are well below the sum of the van der Waals radii for these atoms. These close contacts, as well as packing motifs similar to that of the title compound, were als...
Sulfonamides amines, alcohols, and phenols were efficiently acylated with carboxylic acid anhydrides and chlorides using ZSM-5-SO3H as catalyst under mild and solvent-free conditions. Also, direct esterification of alcohols with carboxylic acids occurred readily in the presence of this catalyst. Different types of amides and esters were obtained in moderate to high yields and purity after a sim...
The use of natural resources as a chemical feedstock for the synthesis of added-value products is gaining interest; as such we report an environmentally friendly method for the synthesis of para-menthane-3,8-diol from natural citronellal oil in 96% yield, under solvent free aqueous conditions. The acylation of para-menthane-3,8-diol with various acid anhydrides over polymer-supported scandium t...
Reaction of 6-arylamino-1,3-dialkyluracils with anhydrides of polyfluorocarboxylic acids in the presence of pyridine and subsequent cyclization with concentrated H2SO4 gave the corresponding 1,3-dialkyl-5-(polyfluoroalkyl)pyrimido[4,5-b]quinoline-2,4(1H,3H)-diones (5-polyfluoroalkyl-5-deazaalloxazines). The reactivity of these compounds towards nucleophilic reagents, such as sodium cyanoborohyd...
A versatile solid-phase approach to sequence-defined polyamidoamines was developed. Four different Fmoc-polyamino acid building blocks were synthesized by selective protection of symmetrical oligoethylenimine precursors followed by introduction of a carboxylic acid handle using cyclic anhydrides and subsequent Fmoc-protection. The novel Fmoc-polyamino acids were used to construct polyamidoamine...
Most of the methoxy-8H-dibenzo[a,g]isoquinolin-8-ones 3a-h and their acetoxy derivatives 6a-e were synthesized by condensation of 1-oxo-1,2,3,4-tetrahydroisoquinolines 4a-c and homophthalic acid anhydrides 5a and b, ether cleavage and acetylation. These protoberberinones were tested for cytostatic activity in vitro using MDA-MB-231 mammary tumor cells and for interaction with native calf thymus...
Controlled routes to prepare polyesters and polycarbonates are of interest due to the widespread application of these materials and the opportunities provided to prepare new copolymers. Furthermore, ring-opening copolymerization may enable new poly(ester-carbonate) materials to be prepared which are inaccessible using alternative polymerizations. This review highlights recent advances in the ri...
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