نتایج جستجو برای: acetates esters
تعداد نتایج: 29185 فیلتر نتایج به سال:
The enzymatic kinetic resolution (EKR) of racemic alcohols or esters is a broadly recognized methodology for the preparation these compounds in optically active form. Although EKR approaches have been developed enantioselective transesterification vast number secondary hydrolysis their respective esters, to date, there no report bio- chemo-catalytic asymmetric synthesis non-racemic possessing 1...
The harvest time of grapes is a major determinant berry composition and the wine quality, it usually established through empirical testing main biochemical parameters berry. In this work, we studied how ripening stage Aglianico modulates key secondary metabolites wines, phenolics volatile compounds. Specifically, analyzed compared four stages corresponding to total soluble solids 18, 20, 22, 25...
The aim of the laboratory experiments presented here is to find a set of thermosensitive tracers to identify thermal characteristics in deep geothermal reservoirs during the long-term operation of a power plant. In the near future several short-term push-pull experiments are planned at different test-sites in northern Europe. As a first step we focus on tracers which fulfill the requirements of...
3,7-Dimethylpentadecan-2-ol and 3-methylpentadecan-2-ol were identified in female whole body extracts from the two pine sawfly species Gilpinia frutetorum and Gilpinia socia. This is the first observation of 3-methylpentadecan-2-ol in extracts of a female pine sawfly species. Synthetic and highly pure stereoisomers of 3,7-dimethylpentadecan-2-ol and 3-methylpentadecan-2-ol were used to verify t...
Wines from four Galician white varieties (Albariño, Loureira, Treixadura and Dona Branca) with 1992 to 1995 vintages have been analysed, in order to obtain their characterisation by the aromatic index. Monoterpenes, higher alcohols, ethyl esters, fatty acids, acetates, volatile phenols and heavy sulphur compounds were analysed by gas chromatography alone and together with mass spectrometry. Fla...
2,3-Unsaturated-4-keto glycosyl acetates were found to exhibit low reactivity under several glycosylation conditions. Chemoselective glycosylations were effectively performed using 2,3-unsaturated glycosyl and 2,3-dideoxy glycosyl acetates as armed glycosyl donors, and 2,3-unsaturated-4-keto glycosyl acetates as disarmed glycosyl donors.
Tandem reactions use consecutive reaction steps to efficiently synthesize compounds of high molecular complexity. This paper presents a tandem Pd-catalyzed Heck and alkoxycarbonylation reaction for the stereoselective synthesis of (E)-oxindolylidene acetates. The mechanism underlying the Pd-catalyzed tandem reaction involves the syn-carbopalladation of ynamides followed by alkoxycarbonylation w...
The structure of the lignin in wheat straw has been investigated by a combination of analytical pyrolysis, 2D-NMR, and derivatization followed by reductive cleavage (DFRC). It is a p-hydroxyphenyl-guaiacyl-syringyl lignin (with an H:G:S ratio of 6:64:30) associated with p-coumarates and ferulates. 2D-NMR indicated that the main substructures present are β-O-4'-ethers (∼~75%), followed by phenyl...
Analyses of the hexane washes of antennae, forelegs and whole bodies of Helicoverpa zea, Heliothis virescens, and Manduca sexta revealed notable differences in the components of the cuticular coatings of each species. Most striking were the differences between the cuticular coatings of male and female antennae of both H. zea and H. virescens. Novel esters of short-chain acids (C2-C4) and long-c...
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