3142-58-3Relevant academic research and scientific papers
Hydrotalcite-catalyzed alkylation of 2,4-pentanedione
Cativiela,Figueras,Garcia,Mayoral,Zurbano
, p. 1745 - 1750 (1995)
A synthetic anionic clay, hydrotalcite (Mg/Al = 2.8), calcined under dry air at 450°C has proved to be an efficient catalyst for the selective C-monoalkylation of 2,4-pentanedione with reactive alylating reagents.
Extended reaction scope of thiamine diphosphate dependent cyclohexane-1,2-dione hydrolase: From C-C bond cleavage to C-C bond ligation
Loschonsky, Sabrina,Wacker, Tobias,Waltzer, Simon,Giovannini, Pier Paolo,McLeish, Michael J.,Andrade, Susana L. A.,Müller, Michael
supporting information, p. 14402 - 14406 (2015/02/19)
ThDP-dependent cyclohexane-1,2-dione hydrolase (CDH) catalyzes the CC bond cleavage of cyclohexane-1,2-dione to 6-oxohexanoate, and the asymmetric benzoin condensation between benzaldehyde and pyruvate. One of the two reactivities of CDH was selectively knocked down by mutation experiments. CDH-H28A is much less able to catalyze the CC bond formation, while the ability for CC bond cleavage is still intact. The double variant CDH-H28A/N484A shows the opposite behavior and catalyzes the addition of pyruvate to cyclohexane-1,2-dione, resulting in the formation of a tertiary alcohol. Several acyloins of tertiary alcohols are formed with 54-94% enantiomeric excess. In addition to pyruvate, methyl pyruvate and butane-2,3-dione are alternative donor substrates for CC bond formation. Thus, the very rare aldehyde-ketone cross-benzoin reaction has been solved by design of an enzyme variant.
Novel C2-symmetric chiral O,N,N,O-tetradentate 2,2-bipyridyldiolpropane ligands: Synthesis and application in asymmetric diethylzinc addition to aldehydes
Shih, Yi-Shan,Boobalan, Ramalingam,Chen, Chinpiao,Lee, Gene-Hsian
, p. 327 - 333 (2014/04/03)
First synthesis of C2-symmetric chiral O,N,N,O-tetradentate 2,2-bipyridyldiolpropane ligands is described. The Mukaiyama-Michael reaction was applied as an important reaction for the synthesis of 2,2-bipyridylpropane 9. Among the ligands synthesized, ligand 11 exhibits excellent chiral induction (up to 97% ee) in diethylzinc addition to various aldehydes. The use of additional Lewis acid such as Ti(OiPr)4 in diethylzinc addition reaction is not required for the present catalytic system.
Synthesis and biological evaluation of new curcumin derivatives as antioxidant and antitumor agents
Bayomi, Said M.,El-Kashef, Hassan A.,El-Ashmawy, Mahmoud B.,Nasr, Magda N. A.,El-Sherbeny, Magda A.,Badria, Farid A.,Abou-Zeid, Laila A.,Ghaly, Mariam A.,Abdel-Aziz, Naglaa I.
, p. 1147 - 1162 (2013/04/10)
Twenty-four new compounds were prepared, taking curcumin as a lead, in order to explore their antioxidant and antitumor properties. The capacities of these derivatives to scavenge the 2,2′-azinobis(3-ethylbenzothiazoline-6- sulfonic acid) radical cation (ABTS.+), and to protect human red blood cells (RBCs) from oxidative haemolysis were investigated. In addition, the percentage viability of different cell lines (Hep G2, WI38, VERO and MCF-7) was tested. The result of the antitumor testing was generally in accordance with those of the antioxidant assays. Compounds which bear o-methoxy substitution to the 4-hydroxy function in the phenyl ring (7g, 5g and 3g) exhibited significantly higher ABTS.+-scavenging, antihaemolysis, and antitumor activities than other derivatives. In addition, molecular modelling studies were carried out for biologically active and inactive compounds, to study the structure-activity relationship, with the aim to elucidate which portions of the molecules are critical for the antioxidant and antitumor activity.
Diastereo- and regioselective synthesis of diquinanes and related systems from tricyclo[3.3.0.02,4]octanes by chemical electron transfer (CET)
Adam,Heidenfelder,Sahin
, p. 1163 - 1170 (2007/10/02)
A new synthetic methodology for diquinanes by one-electron oxidation of tricyclo[3.3.0.02,4]octanes and subsequent stereocontrolled rearrangement is provided. The latter compounds are conveniently accessible through acid-catalyzed isopyrazole cycloaddition, followed by hydrogenation and photoextrusion of molecular nitrogen. The oxidative rearrangement of the tricyclooctanes proceeds catalytically and cleanly to afford regio- and diastereoselectively the corresponding diquinanes.
Synthesis and Thermolysis of Ketal Derivatives of 3-Hydroxy-1,2-dioxolanes
Baumstark, A. L.,Vasquez, P. C.,Chen, Y.-X.
, p. 6692 - 6696 (2007/10/02)
3--3,4,4,5-tetramethyl-5-phenyl-1,2-dioxolane (2), 3-methoxy-3,4,4,5-tetramethyl-5-phenyl-1,2-dioxolane (3), and 3-acetoxy-3,4,4,5-tetramethyl-5-phenyl-1,2-dioxolane (4) were synthesized from the corresponding 3-hydroxy-1,2-dioxolane (1a) under basic conditions. 3-Acetoxy-4,4-dimethyl-3,5,5-triphenyl-1,2-dioxolane (5) was also synthesized via this approach.Under acidic conditions, 3-hydroxy-1,2-dioxolane 1a underwent quantitative decomposition to phenol and 3,3-dimethyl-2,4-pentanedione.This competing degradation was dependent on the nature of the substituents at position-5.Methyl groups at position-5 slowed the degradative rearrangement whereas phenyl groups favored it. 3-Methoxy- and 3-(allyloxy)-4,4,5,5-tetramethyl-3-phenyl-1,2-dioxolanes (6, 7) were synthesized under acidic conditions from the appropriate 1,2-dioxolane precursors and the corresponding alcohols.At 60 deg C, derivatized 1,2-dioxolanes 2-7 were found to be more stable than the corresponding 3-hydroxy-1,2-dioxolanes.The first order rate constants for the thermolysis of 1,2-dioxolanes 2-7 were determined.Product studies showed that thermolysis of 2-5 yielded pairs of ketones and derivatized carboxylic acids.In addition to R-group migration products, an acetoxy migration product was observed for the thermolysis of 4.Thermolysis of 6 at 60 deg C in benzene yielded methyl benzoate and pinacolone, quantitatively.Thermolysis of 7 yielded products analogous to those for 6.No evidence for internal trapping of radicals by the carbon-carbon double bond of the allyloxy group in 7 was found.The thermolysis appeared to proceed with peroxy bond homolysis as the rate-determining step.Subsequent β-scissions of the intermediate 1,5-oxygen diradical with interesting rearrangements that show a high preference for alkyl vs phenyl migration account for the observed product distributions.The results suggest that the β-scission/rearrangement mechanism may not be concerted but rather stepwise to yield 1,3-diradical and carbonyl fragments.
Surface-mediated Solid-phase Reaction. Part 2. Highly Selective Mono- and Di-C-alkylation of 1,3-Dicarbonyl Compounds on the Surface of Alumina
Ranu, Brindaban C.,Bhar, Sanjay
, p. 365 - 368 (2007/10/02)
Highly selective mono- and di-C-alkylation of 1,3-dicarbonyl compounds with different, structurally varied alkyl halides has been achieved in high yields through a simple solvent-free reaction on the surface of alumina impregnated with sodium or potassium alkoxide.
Synthesis of 4,4-Dimethyl-3,4-dihydro-3,3,5-trisubstituted-2H-pyrazoles and N-Benzoyl Derivatives: Method for "Hydrolysis" of Unreactive Amides and Carbamates
Baumstark, Alfons L.,Choudhary, Anil,Vasquez, Pedro C.,Dotrong, My
, p. 291 - 294 (2007/10/02)
Addition of organolithium reagents to 4,4-dimethyl-3,5-disubstituted-4H-pyrazoles produced a series of 4,4-dimethyl-3,4-dihydro-3,3,5-trisubstituted-2H-pyrazoles, 2-6, in good yield.The reaction was stereoselective: addition of organolithium compounds occurred only to carbon-3 of 4,4-dimethyl-3-alkyl-5-aryl-4H-pyrazoles.The 3,4-dihydro-2H-pyrazoles were found to be of high sensitivity to oxygen.For long term storage and ease of handling, N-benzoyl derivatives were synthesized.Removal of protecting group could not be accomplished by use of many standard sets of conditions.Deprotection was accomplished in high yield by reaction of the N-benzoyl-4,4-dimethyl-3,4-dihydro-3,3,5-trisubstituted-2H-pyrazoles with anhydrous potassium t-butoxide in toluene in the presence of a phase transfer catalyst (18-Crown-6).Cleavage of a N-carbamate derivative was also achieved by this phase transfer approach.This methodology should be applicable to the hydrolysis of unreactive amides and carbamates in general.
Convenient, High-Yield Method for the Methylation of 1,3-Diketones
Choudhary, Anil,Baumstark, Alfons L.
, p. 688 - 690 (2007/10/02)
A general method for the facile dimethylation of 1,3-diketones is presented.The method involves the use of readily available, inexpensive reagents and is carried out under mild conditions.Monomethylation may be carried out by slight modification (simplification) of the procedure.Several examples are presented which show that the method is applicable to alkylations with primary halides as well.Isolated yields for monoalkylation are approximately 95percent while those for dialkylation are ca. 90percent.Alkylation is taking place by the reaction of the enolates of 1,3-diketones with alkyl halides.
Azo Bridges from Azines, VI. - Substituted Isopyrazoles as Electron-deficient Dienes for the Synthesis of 2,3-Diazabicycloheptenes and their Photochemistry
Beck, Karin,Huenig, Siegfried
, p. 477 - 484 (2007/10/02)
The ++2> cycloaddition of isopyrazoles (4H-pyrazoles) 3c-e and cyclopentadiene, norbornene, and norbornadiene leads to the azo-bridged products 5, 8, 11, and 12c-e.Irradiation of 5e, 8e, and 11e expectedly produces the tricycles 13, 15, and 17 by loss of nitrogen.In contrast, as a result of the parallel arrangement of the C=C/N=N bonds, the isomers 12c-e are transformed nearly quantitatively into diazetidines 14, 16, and 18; despite the pronounced photolability of the diazabicycloheptene moiety in 12, cycloaddition is preferred over nitrogen elimination.
