نتایج جستجو برای: β unsaturated compounds

تعداد نتایج: 410276  

Cyclodextrins (CDs) are a family of cyclic oligosaccharides which are composed of α (1,4) -linked glucopyranose subunits. Thebest-characterized forms are α, β and γ CD which are consisted of six, seven and eight D-glucose units, respectively. Cyclodextrins are produced from starch by enzymatic degradation. These macrocyclic carbohydrates with polar internal cavities can form complexes with and ...

An efficient synthesis of chromenylphenylpropanone derivatives as warfarine-like analogues was developed by the Michael addition of 4-hydroxycoumarin to α,β-unsaturated compounds in the presence of polyvinylpolypyrrolidone supported antimony(III) chloride (PVPP-SbCl3) as a new polymeric Lewis acid catalyst in chloroform at reflux conditions without formation of 2,4-...

Journal: :Journal of natural products 2014
Yuan-Bin Cheng Yi-Ting Chien Jin-Ching Lee Chin-Kai Tseng Hui-Chun Wang I-Wen Lo Yi-Hung Wu Sheng-Yang Wang Yang-Chang Wu Fang-Rong Chang

Fractionation of an ethanol-soluble extract of the seeds of Swietenia macrophylla yielded six new limonoids, swielimonoids A-F (1-6), along with 20 known compounds. Compounds 1 and 2, mexicanolide-type limonoids, were assigned with an α,β-unsaturated δ-lactone moiety (ring D) and a C═C bond between C-8 and C-30. Compounds 3-6 could be categorized as highly oxygenated phragmalin-type limonoids. ...

2004
Seong-Jin Hong Mi-Hye Lee Chang-Hee Lee

meso-Functionalized dipyrromethanes 6-10 were synthesized by acid-catalyzed addition of pyrrole to αposition of 2-alkenyl pyrroles. The regiochemistry of the reaction can be explained by either the formation of more stable carbocation intermediate or β-addition of α,β-unsaturated carbonyl compounds. The starting 2alkenyl pyrroles were synthesized by Aldol condensation of 2-formylpyrrole with ac...

Ammonium monovanadate (NH4VO3) has been devoted as an efficient, commercially available, eco-friendly and reusable catalyst for the synthesis of bis(indolyl)methanes (BIMs), oxindole derivatives and also Michael adducts of indoles at 50 °C under solvent-free conditions. The reusability of this solid acid catalyst in addition with its selectivity has also been examined.

Journal: :Chemistry: A European Journal 2023

Micellar photocatalysis allows for a simple and benign reaction set-up using water as the solvent without need oxygen-removing protocols. Blue light (456 nm) is absorbed by photocatalyst [2+2] photocycloaddition to occur between α,β-unsaturated carbonyl compounds activated alkenes. The observed reactivity aldehydes completely turned on use of micellar solution opposed organic solvents. More inf...

Journal: :journal of agricultural science and technology 2014
j. guo h. wu l. du w. zhang j. yang

ginger (zingiber officinale roscoe) contains the biological properties of the major standard non–volatile pungent compounds of ginger, namely, [6]–, [8]–, and [10]–gingerols, as well as [6]– , [8]–, and [10]–shogaols. so far, the comparative antioxidant potencies among shogaols and gingerols have not been studied in detail and reported. accordingly, this study aimed to examine and compare the a...

Journal: :Angewandte Chemie 2023

Enantioselective reduction reactions are privileged transformations for the construction of trisubstituted stereogenic centers. While these include established synthetic strategies, such as asymmetric hydrogenation, methods based on enantioselective addition hydridic reagents to electrophilic prochiral substrates have also gained importance. In this context, conjugate (ACR) α,β-unsaturated comp...

نمودار تعداد نتایج جستجو در هر سال

با کلیک روی نمودار نتایج را به سال انتشار فیلتر کنید