18402-83-0Relevant academic research and scientific papers
Selective cleavage of ketals and acetals under neutral, anhydrous conditions using triphenylphosphine and carbon tetrabromide
Johnstone, Craig,Kerr, William J.,Scott, James S.
, p. 341 - 342 (1996)
A convenient method for the selective removal of ketal and acetal protection under mild, neutral, anhydrous conditions using PPh3 and CBr4 is described.
REACTIVITY OF THE 1-t.BUTYLTHIO-3-METHOXY-1-ALKENES TOWARDS METALATING AGENTS, I. REGIOSELECTIVE DEPROTONATION AT EITHER ONE OF THE TWO OLEFINIC SITES OF THE Z-ISOMERS
Ekogha, C. Bibang Bi,Ruel, O.,Julia, S. A.
, p. 4825 - 4828 (1983)
THF solutions of the title Z-isomers (with the exception of the propenyl compound) at -78 degC produce either(i) the 1-metalated derivatives when treated with potassium t.butoxide and n.butyllithium or (ii) the 2-lithiated derivatives when sec.butyllithium is the metalating agent.Both metalated derivatives become new equivalents of the hypothetical anions I and II respectively.
Efficient Transformation of Methyl Propargyl Ethers into α,β-Unsaturated Ketones
Fukuda, Yukitoshi,Utimoto, Kiitiro
, p. 2013 - 2015 (1991)
Methyl propargyl ethers, obtained from carbonyl compounds by successive treatment with an acetylide and MeI, were easily converted to the corresponding α,β-unsaturated ketone by regioselective hydration of acetylenic moiety followed by elimination of methanol under the catalytic action of Au(III).
Characterization of initial reaction intermediates in heated model systems of glucose, glutathione, and aliphatic aldehydes
Wang, Tianze,Zhen, Dawei,Tan, Jia,Xie, Jianchun,Cheng, Jie,Zhao, Jian
, (2019/09/12)
To understand the effect of lipid degradation on Maillard formation of meaty flavors, initial reaction intermediates in model systems of glucose–glutathione with hexanal, (E)-2-heptenal, or (E,E)-2,4-decadienal were identified by HPLC–MS and by NMR. Besides Amadori compounds, hemiacetals and thiazolidines via addition of sulfhydryl to carbonyl or to the conjugated olefinic bond were found. Concentrations of all intermediates increased with reaction time while degradation of the intermediates with a glutathione moiety helped formation of thiazolidines with cysteinylglycine. The unsaturated aldehydes (E)-2-heptenal and (E,E)-2,4-decadienal exhibited high reactivity against glucose for glutathione, yielding higher levels of intermediate compounds than from glucose. Heating prepared intermediates reversibly released the original aldehydes, which caused various compounds formed by retro-aldol, oxidation, etc. to react with H2S and NH3. Among them, formation pathways including 3-nonen-2-one, 2-hexanoylfuran, and six dialkylthiophenes (e.g., 2-ethyl-5-(1-methylbutyl)thiophene) were proposed for the first time.
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.
Cationic Co(I)-intermediates for hydrofunctionalization reactions: Regio- A nd enantioselective cobalt-catalyzed 1,2-hydroboration of 1,3-dienes
Duvvuri, Krishnaja,Dewese, Kendra R.,Parsutkar, Mahesh M.,Jing, Stanley M.,Mehta, Milauni M.,Gallucci, Judith C.,Rajanbabu
, p. 7365 - 7375 (2019/05/16)
Much of the recent work on catalytic hydroboration of alkenes has focused on simple alkenes and styrene derivatives with few examples of reactions of 1,3-dienes, which have been reported to undergo mostly 1,4-additions to give allylic boronates. We find that reduced cobalt catalysts generated from 1,n-bis-diphenylphosphinoalkane complexes [Ph2P-(CH2)n-PPh2]CoX2; n = 1-5) or from (2-oxazolinyl)phenyldiarylphosphine complexes [(G-PHOX)CoX2] (G = 4-substituent on oxazoline ring) effect selective 1,2-, 1,4-, or 4,3-additions of pinacolborane (HBPin) to a variety of 1,3-dienes depending on the ligands chosen. Conditions have been found to optimize the 1,2-additions. The reactive catalysts can be generated from the cobalt(II)-complexes using trimethylaluminum, methyl aluminoxane, or activated zinc in the presence of sodium tetrakis[(3,5-trifluoromethyl)phenyl]borate (NaBARF). The complex, (dppp)CoCl2, gives the best results (ratio of 1,2-to 1,4-addition >95:5) for a variety of linear terminal 1,3-dienes and 2-substituted 1,3-dienes. The [(PHOX)CoX2] (X = Cl, Br) complexes give mostly 1,4-addition with linear unsubstituted 1,3-dienes, but, surprisingly, selective 1,2-additions with 2-substituted or 2,3-disubstituted 1,3-dienes. Isolated and fully characterized (X-ray crystallography) Co(I)-complexes, (dppp)3Co2Cl2 and [(S,S)-BDPP]3Co2Cl2, do not catalyze the reaction unless activated by a Lewis acid or NaBARF, suggesting a key role for a cationic Co(I) species in the catalytic cycle. Regio- A nd enantioselective 1,2-hydroborations of 2-substituted 1,3-dienes are best accomplished using a catalyst prepared via activation of a chiral phosphinooxazoline-cobalt(II) complex with zinc and NaBARF. A number of common functional groups, among them,-OBn,-OTBS,-OTs, N-phthalimido-groups, are tolerated, and er's > 95:5 are obtained for several dienes including 1-alkenylcycloalk-1-enes. This operationally simple reaction expands the realm of asymmetric hydroboration to provide direct access to a number of nearly enantiopure homoallylic boronates, which are not readily accessible by current methods. The resulting boronates have been converted into the corresponding alcohols, potassium trifluororoborate salts, N-BOC amines, and aryl derivatives by C-BPin to C-aryl transformation.
Acyl/aroyl Meldrum's acid as an enol surrogate for the direct organocatalytic synthesis of α,β-unsaturated ketones
Khopade, Tushar M.,Warghude, Prakash K.,Mete, Trimbak B.,Bhat, Ramakrishna G.
supporting information, p. 197 - 200 (2018/12/13)
The operationally simple, robust and straightforward organocatalytic protocol is developed for the synthesis of E-selective α,β-unsaturated ketones. The method utilizes simple and easily accessible starting materials such as Meldrum's acid, carboxylic acid, aldehyde and simple bifunctional amine catalyst. The tandem organocatalytic process utilizes acyl/aroyl Meldrum's acid as an enol surrogate for the effective Doebner-Knoevenagel type condensation reactions. A wide variety of aldehydes, carboxylic acids and base sensitive functional groups are well tolerated under the mild reaction conditions.
Design, synthesis and antimycobacterial activities of 1-methyl-2-alkenyl- 4(1H)-quinolones
Wube, Abraham A.,Hüfner, Antje,Thomaschitz, Christina,Blunder, Martina,Kollroser, Manfred,Bauer, Rudolf,Bucar, Franz
experimental part, p. 567 - 579 (2011/03/17)
A series of 23 new 1-methyl-2-alkenyl-4(1H)quinolones have been synthesized and evaluated in vitro for their antimycobacterial activities against fast growing species of mycobacteria, such as Mycobacterium fortuitum, M. smegmatis and M. phlei. The compounds displayed good to excellent inhibition of the growth of the mycobacterial test strains with improved antimycobacterial activity compared to the hit compound, evocarpine. The most active compounds, which possessed chain length of 11-13 carbons at position-2 displayed potent inhibitory effects with an MIC value of 1.0 mg/L. In a human diploid embryonic lung cell line, MRC-5 cytotoxicity assay, the alkaloids showed weak to moderate cytotoxic activity. Biological evaluation of these evocarpine analogues on the less pathogenic fast growing strains of mycobacteria showed an interesting antimycobacterial profile and provided significant insight into the structure-activity relationships.
Palladium/benzoquinone-catalyzed electrochemical oxidation of alcohols under anaerobic conditions
Amatore, Christian,Cammoun, Chama,Jutand, Anny
, p. 2173 - 2178 (2008/02/10)
Primary and secondary alcohols are oxidized to aldehydes and ketones, respectively, under anaerobic conditions in DMF at 80°C, in the presence of a base and catalytic amounts of Pd(OAc)2 and p-benzoquinone. The latter oxidizes the transient Pd(0) formed in the catalytic cycle to Pd(II) and p-hydroquinone is re-oxidized electrochemically. Georg Thieme Verlag Stuttgart.
ORGANOCATALYSTS AND METHODS OF USE IN CHEMICAL SYNTHESIS
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Page/Page column 64-65; 119-120, (2010/02/15)
The present invention pertains generally to compositions comprising organocatalysts that facilitate stereo-selective reactions and the method of their synthesis and use. Particularly, the invention relates to metal-free organocatalysts for facilitation of stereo--selective reactions, and the method of their synthesis and use. These compounds have the structure of the Formulas (I) and (II). Where X is independently selected from CH2, N-Ra, O, S or C=O; Y is CH2, N-Ra, O, S or C=O, with the proviso that at least one of X or Y is CH2, and preferably both of X and Y are CH2; Ra is H, an optionally substituted C1-C12 alkyl, preferably an optionally substituted C1-C6alkyl including a C3-C6 cyclic alkyl group, or an optionally substituted aryl group, preferably an optionally substituted phenyl group; Rb is H, an optionally substituted C1-C12 alkyl, preferably an optionally substituted C1-C6 acyclic or a a C3-C6 cyclic alkyl group, CHO, N(Me)O, CO(S)Ra or the group of Formula (III). Where Rc and Rd are each independently H, F, C1, an optionally substituted C1-C20 alkyl, preferably an optionally substituted C1-C12 alkyl, more preferably a C1-C6 alkyl, and an optionally substituted aryl group, or together Rc and Rd form an optionally substituted carbocyclic or optionally substituted heterocyclic ring; R1 is OH, OR, NR'R", NHC(=O)R, NHSO2R; R2 is H, F, C1, an optionally substituted C1-C20 alkyl, preferably an optionally substituted C1-C6 alkyl, an optionally substituted aryl group or a =O group (which establishes a carbonyl group with the carbon to which =O is attached; R3 is H, OH, F, C1, Br, I, Cl, an optionally substituted C1-C20 alkyl, alkenyl or alkynyl ("hydrocarbyl") group, preferably an optionally substituted C1-C6 alkyl, or an optionally substituted aryl, such that the carbon to which R3 is attached has an R or S configuration; R is H, an optionally substituted C1-C20 alkyl, preferably an optionally substituted C1-C6 alkyl, or an optionally substituted aryl group, R' and R" are each independently H, an optionally substituted C1-C20 alkyl group, preferably an optionally substituted C1-C6 alkyl, or an optionally substituted aryl group; or together R' and R" form an optionally substituted heterocyclic, preferably a 4 to 7 membered optionally substituted heterocyclic group or an optionally substituted heteroaryl ring with the nitrogen to which R' and R" are attached; and wherein said compound is free from a metal catalyst.
