20048-01-5Relevant academic research and scientific papers
Reaction of aromatic aldehydes with β-dicarbonyl compounds in a catalytic system: Piperidinium acetate - 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid
Putilova,Troitskii,Zlotin
, p. 1233 - 1238 (2005)
Condensation of aromatic (heteroaromatic) aldehydes with 1,3-dicarbonyl compounds under the 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) ionic liquid - piperidinium acetate catalytic system (0.2 equiv. of each component) in the absence of a solvent affords, depending on the structures of the reagents, 2-arylidene derivatives of methyl acetoacetate and acetylacetone, diethyl 2,4-bis(trifluoroacetyl)-3-phenylpentanedioate, or dimethyl 2-aryl-4-hydroxy-6-oxocyclohexane-1,3-dicarboxylates. The reactions of the resulting 2-arylidene derivatives with O-methylisourea in the [Bmim][BF 4] ionic liquid produced methyl 2-methoxy-4-methyl-6- aryldihydropyrimidine-5-carboxylates and 1-(2-methoxy-4-methyl-6- phenyldihydropyrimidin-5-yl)ethanone (mixtures of 3,6- and 1,6-dihydro isomers), which were transformed into the corresponding 3,4-dihydropyrimidin-2(1H)-one derivatives.
An access to α, β-unsaturated ketones via dual cooperative catalysis
Syamala, Lakshmi V.R. Babu,Khopade, Tushar M.,Warghude, Prakash K.,Bhat, Ramakrishna G.
supporting information, p. 88 - 91 (2018/12/05)
A dual cooperative organocatalytic approach for the synthesis of α, β-unsaturated ketones is described. This one pot transformation is realized via a domino Knoevenagel-Michael-retro Michael reaction sequence. Various aliphatic ketones reacted smoothly with aromatic as well as aliphatic aldehydes in presence catalytic amount of Meldrum's acid and bifunctional amine. The highlights of this protocol are the easy availability of catalysts, high selectivity, and functional group tolerance. The reaction proved to highly E-selective with no side products emanating from self-condensation, unlike the base-mediated reactions.
Cross-linked polystyrene-TiCl4 complex as a reusable Lewis acid catalyst for solvent-free Knoevenagel condensations of 1,3-dicarbonyl compounds with aldehydes
Rahmatpour, Ali,Goodarzi, Niloofar
, p. 24 - 31 (2019/03/08)
Cross-linked polystyrene copolymer beads with the average particle size in the range of (50–80 mesh size) were prepared by a new method, characterized and functionalized with titanium tetrachloride to afford the corresponding polystyrene?titanium tetrachloride complex in one step reaction and characterized by FT-IR, UV, TGA, DSC, XRD, SEM, BET. This polymer metal complex (PS/TiCl4) was used as a heterogeneous, recoverable, reusable Lewis acid for solvent-free Knoevenagel condensations of 1,3-diketones with aromatic aldehydes under green and mild conditions. The rate of reactions was found to decrease with an increasing percentage of crosslinking and the mesh size of the copolymer beads. This complex showed good stability and catalytic activity in the Knoevenagel reactions.
1,4-dihydropyridine derivatives
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, (2008/06/13)
1,4-Dihydropyridine derivatives of formula: STR1 wherein Ar1 represents an aromatic hydrocarbon group or an aromatic heteromonocyclic or heterobicyclic group containing therein 1 to 3 atoms selected from the group consisting of oxygen, sulfur and nitrogen; R1 represents a hydrocarbon group which may have one or more substituents; A represents (i) a straight chain or branched chain unsaturated hydrocarbon group, (ii) a cyclic unsaturated hydrocarbon group, or (iii) a group selected from the group consisting of --R--O--N=CH--, --R--N=N--, --R--CH=N-- and --R--N=CH--, in which R is an alkylene group having 1 to 6 carbon atoms; B represents an alkylene or alkenylene group having 1 to 3 carbon atoms, which may have a substituent; Ar2 represents an aromatic hydrocarbon group or a heterocyclic group; Ar3 represents a heterocyclic group which may have one or more substituents; and n is 0 or 1, and the corresponding optical active 1,4-dihydropyridine derivatives, having an optically active cite as indicated by *, have both superior vasodilative and platelet aggregation inhibiting activities.
