- "one-Pot" Synthesis of γ-Pyrones from Aromatic Ketones/Heteroarenes and Carboxylic Acids
-
Despite the various attractive properties of γ-pyrones, there are still some deficiencies in their synthetic approaches such as lower atom economy, multistep processes, and prefunctionalization of the reagents. In this work, an efficient and simple (CF3CO
- Sun, Xiangyu,Gong, Ming,Huang, Mengmeng,Li, Yabo,Kim, Jung Keun,Kovalev, Vladimir,Shokova, Elvira,Wu, Yangjie
-
-
Read Online
- Mechanism of formation of sulphur aroma compounds from l-ascorbic acid and l-cysteine during the Maillard reaction
-
The sulphur aroma compounds produced from a phosphate-buffered solution (pH 8) of l-cysteine and l-, l-[1-13C] or l-[4-13C] ascorbic acid, heated at 140 ± 2 °C for 2 h, were examined by headspace SPME in combination with GC-MS. MS data indicated that C-1 of l-ascorbic acid was not involved in the formation of sulphur aroma compounds. The sulphur aroma compounds formed by reaction of l-ascorbic acid with l-cysteine mainly contained thiophenes, thiazoles and sulphur-containing alicyclic compounds. Among these compounds, 1-butanethiol, diethyl disulphide, 5-ethyl-2-methylthiazole, cis and trans-3,5-dimethyl-1,2,4-trithiolane, thieno[2,3-b]thiophene, thieno[3,2-b]thiophene, cis and trans-3,5-diethyl-1,2,4-trithiolane, 1,2,5,6-tetrathiocane, 2-ethylthieno[2,3-b]thiophene, 2,4,6-trimethyl-1,3,5- trithiane and cyclic octaatomic sulphur (S8) were formed solely by l-cysteine degradation, and the rest by reaction of l-ascorbic acid degradation products, such as hydroxybutanedione, butanedione, acetaldehyde, acetol, pyruvaldehyde and formaldehyde with l-cysteine or its degradation products, such as H2S and NH3. A new reaction pathway from l-ascorbic acid via its degradation products was proposed.
- Yu, Ai-Nong,Tan, Zhi-Wei,Wang, Fa-Song
-
experimental part
p. 1316 - 1323
(2012/06/30)
-
- Synthesis of aryl ketones by palladium(II)-catalyzed decarboxylative addition of benzoic acids to nitriles
-
An efficient, sustainable method for the preparation of aryl ketones from ortho-substituted benzoic acids proceeds through their decarboxylation to generate an aryl-palladium species, followed by addition to a nitrile and hydrolysis of the intermediate ketimine.
- Lindh, Jonas,Sjoeberg, Per J. R.,Larhed, Mats
-
supporting information; experimental part
p. 7733 - 7737
(2011/01/05)
-
- A highly active ytterbium(III) methide complex for truly catalytic Friedel-Crafts acylation reactions
-
The Friedel-Crafts acylation of anisole with acetic anhydride using ytterbium(III) tri[tris(nonafluorobutanesulfonyl)methide] was studied with respect to catalyst loading. A strong inhibitory effect due to the product became apparent from doping experiments and from examination of the kinetic data. This understanding allowed catalyst loadings to be reduced to as little as 0.1 mol% for effective acylation under a suitable temperature and pressure regime.
- Barrett, Anthony G. M.,Bouloc, Nathalie,Braddock, D. Christopher,Chadwick, David,Henderson, David A.
-
p. 1653 - 1656
(2007/10/03)
-
- THE STAGE CHARACTER OF THE OXIDATION OF DIALKYLTHIOPHENES
-
The reasons for the stage character of the oxidation of dialkylthiophenes catalyzed by a cobalt bromide catalyst are examined.The stage character of oxidation is due to the deactivation of the catalyst by the corresponding alcohol formed during oxidation.At the first stage of the process only the product from oxidation of the α-alkyl group, i.e., the corresponding ketone, ester, and thiophenecarboxylc acid, are formed.The rate constants for their formation were calculated.
- Volkov, M. N.,Kazakova, O. A.
-
p. 370 - 373
(2007/10/02)
-
- CATALYTIC ACTIVITY OF THE CARBOXYLATE COMPLEXES OF COBALT(II) WITH NITROGEN-CONTAINING HETEROCYCLIC LIGANDS IN THE LIQUID-PHASE OXIDATION OF DIALKYLTHIOPHENES
-
The dimeric carboxylate complexes of cobalt(II) with pyridine, quinoline, and quinaldine exhibit fairly high catalytic activity in the liquid-phase oxidation of dialkylthiophenes.The monomeric complex with 2,2'-bipyridyl does not exhibit catalytic activity.
- Kazakova, O. A.,Volkov, M. N.,Zelentsov, V. V.
-
p. 2015 - 2019
(2007/10/02)
-
- EFFECT OF NITROGEN-CONTAINING HETEROCYCLIC COMPOUNDS ON THE LIQUID-PHASE OXIDATION OF DIALKYLTHIOPHENES
-
In the presence of a cobalt-bromide catalyst pyridine and quinoline have an activating effect on the liquid-phase oxidation of dialkylthiophenes. 2,2'-Bipyridyl does not have an activating effect.
- Kazakova, O. A.,Volkov, M. N.
-
p. 352 - 356
(2007/10/02)
-
- CATALYZED LIQUID-PHASE OXIDATION OF DIALKYLTHIOPHENES
-
The oxidation of 3-methyl-2-ethylthiophene with molecular oxygen in glacial acetic acid in the presence of cobalt-bromide catalyst was investigated.It was established that there is a dependence of the rate of oxidation of this compound on its concentration, on the catalyst (cobalt acetate) concentration, and on the initiator (NaBr) concentration.The principal oxidation products are 3-methyl-2-acetothienone (III) and 1-(3-methyl-2-thienyl)ethyl acetate, which were isolated and characterized.The reactivity of 3-methyl-2-ethylthiophene in the oxidation reaction is higher than that of 4-methyl-2-ethylthiophene.
- Volkov, M. N.,Kazakova, O. A.
-
p. 553 - 557
(2007/10/02)
-