- Br?nsted Acid-Catalyzed Carbonyl-Olefin Metathesis inside a Self-Assembled Supramolecular Host
-
Carbonyl–olefin metathesis represents a powerful yet underdeveloped method for the formation of carbon–carbon bonds. So far, no Br?nsted acid based method for the catalytic carbonyl–olefin metathesis has been described. Herein, a cocatalytic system based on a simple Br?nsted acid (HCl) and a self-assembled supramolecular host is presented. The developed system compares well with the current benchmark catalyst for carbonyl–olefin metathesis in terms of substrate scope and yield of isolated product. Control experiments provide strong evidence that the reaction proceeds inside the cavity of the supramolecular host. A mechanistic probe indicates that a stepwise reaction mechanism is likely.
- Catti, Lorenzo,Tiefenbacher, Konrad
-
p. 14589 - 14592
(2018/01/27)
-
- Achieving vinylic selectivity in Mizoroki-heck reaction of cyclic olefins
-
In Heck reactions of cyclic olefins, the products usually have aryl groups that end up at the allylic and/or homoallylic position. We herein report new selectivity that adds aryl groups to the vinylic position. Cyclic olefins of various ring size worked well. The desired isomers were produced by palladium-hydride-catalyzed isomerization of the initial products. Thus, a specific catalyst must be used so that it can perform two jobs under one set of reaction conditions. Copyright
- Wu, Xiaojin,Lu, Yunpeng,Hirao, Hajime,Zhou, Jianrong
-
supporting information
p. 6014 - 6020
(2013/06/26)
-
- Synthesis of hexahydrocyclopenta[c]furans by an intramolecular iron-catalyzed ring expansion reaction
-
The intramolecular iron-catalyzed ring expansion reaction of epoxyalkenes was investigated with a preformed iron(salen) [Fe(Salen)] complex. The formal insertion of the alkene into the epoxide generated hexahydrocyclopenta[c]furan derivatives in moderate to good yields and diastereoselectivities depending on other functional groups present in the starting materials. In addition, oxygen-tethered epoxyalkenes were used for the synthesis of lignan isomers. The scope and limitations of the Fe (Salen)-catalyzed process of the reaction are discussed.
- Hilt, Gerhard,Bolze, Patrick,Heitbaum, Maja,Hasse, Katrin,Harms, Klaus,Massa, Werner
-
p. 2018 - 2026
(2008/09/17)
-
- Arenediazonium o-benzenedisulfonimides as efficient reagents for Heck-type arylation reactions
-
Arenediazonium o-benzenedisulfonimides can be used as new and efficient reagents for Heck-type arylation reactions of some common substrates containing C-C multiple bonds, namely ethyl acrylate, acrylic acid, acroleyne, styrene and cyclopentene. The reactions were carried out in an organic solvent, in the presence of Pd(OAc)2 as pre-catalyst, and gave rise to arylated products, for example, ethyl cinnamates, cinnamic acids, cinnamic aldehydes and stilbenes, possessing an (E)-configuration, and 1-arylcyclopentenes, in good to excellent yields. It is noteworthy that all the reactions led to the recovery, in greater than 80% yield, of o-benzenedisulfonimide, recyclable for the preparation of other diazonium salts.
- Artuso, Emma,Barbero, Margherita,Degani, Iacopo,Dughera, Stefano,Fochi, Rita
-
p. 3146 - 3157
(2007/10/03)
-
- Stereoselective synthesis of δ-lactones from 5-oxoalkanals via one-pot sequential acetalization, tishchenko reaction, and lactonization by cooperative catalysis of samarium ion and mercaptan
-
By the synergistic catalysis of samarium ion and mercaptan, a series of 5-oxoalkanals was converted to (substituted) δ-lactones in efficient and stereoselective manners. This one-pot procedure comprises a sequence of acetalization, Tishchenko reaction and lactonization. The deliberative use of mercaptan, by comparison with alcohol, is advantageous to facilitate the catalytic cycle. The reaction mechanism and stereochemistry are proposed and supported by some experimental evidence. Such samarium ion/mercaptan cocatalyzed reactions show the feature of remote control, which is applicable to the asymmetric synthesis of optically active δ-lactones. This study also demonstrates the synthesis of two insect pheromones, (2S,5R)-2-methylhexanolide and (R)-hexadecanolide, as examples of a new protocol for asymmetric reduction of long-chain aliphatic ketones.
- Hsu,Fang
-
p. 8573 - 8584
(2007/10/03)
-