- Acidic-functionalized ionic liquid as an efficient, green and reusable catalyst for hetero-Michael addition of nitrogen, sulfur and oxygen nucleophiles to α,β-unsaturated ketones
-
A series of acidic-functionalized ionic liquids were synthesized and applied to the hetero-Michael addition of nitrogen, sulfur and oxygen nucleophiles to α,β-unsaturated ketones under solvent-free conditions. Notably, 1-methylimidazolium p-toluenesulfoni
- Han, Feng,Yang, Lei,Li, Zhen,Xia, Chungu
-
experimental part
p. 346 - 354
(2012/01/14)
-
- Palladium(II)-catalyzed dicarboxymethylation of chiral allylic alcohols: Chirality transfer affording optically active diesters containing three contiguous chiral centers
-
This manuscript describes the extension of Stille's palladium-catalyzed olefin dicarbonylation reaction to chiral allylic alcohols with chirality transfer to afford the corresponding chiral alcohol functionalized with bis-carbomethoxy esters, containing three contiguous chiral centers, in good to excellent diastereoselectivities (78-98%).
- Hamed, Othman,Henry, Patrick M.,Becker, Daniel P.
-
supporting information; experimental part
p. 3514 - 3517
(2010/09/05)
-
- Direct organocatalytic hydroalkoxylation of α,β-unsaturated ketones
-
The direct addition of a variety of alcohols to in situ activated olefins was observed in the presence of mild bifunctional amine/acid catalysts. Unlike existing methods, the reactions proceed at room temperature and in the absence of transition metals. The use of simple commercially available catalysts, amines and acids makes this an attractive method for the preparation of β-alkoxy ketones, which are prevalent targets and intermediates in organic synthesis.
- Ramachary, Dhevalapally B.,Mondal, Rumpa
-
p. 7689 - 7693
(2007/10/03)
-
- P(RNCH2CH2)3N: Efficient 1,4-addition catalysts
-
The 1,4-addition of primary alcohols, higher nitroalkanes, and a Schiff's base of an α-amino ester to α,β-unsaturated substrates produces the corresponding products in moderate to excellent yields when carried out at -63 to 70°C in the presence of catalytic amounts of the nonionic strong bases P(RNCH2CH2)3N (R = Me, i-Pr, i-Bu) in isobutyronitrile. Diastereoselectivity for the anti form of the product is high in the case of the Schiff's base in the absence of lithium ion. These catalysts are easily removed from the product by either column filtration through silica gel or via aqueous workup.
- Kisanga, Philip B.,Ilankumaran, Palanichamy,Fetterly, Brandon M.,Verkade, John G.
-
p. 3555 - 3560
(2007/10/03)
-
- Hydroxyl-radical-induced reactions of the poly(vinyl methyl ether) model 2,4-dimethoxypentane in the absence and presence of dioxygen: A pulse radiolysis and product study
-
Hydroxyl radicals were generated radiolytically and reacted with 2,4-dimethoxypentane, a low-molecular-weight model of poly(vinyl methyl ether). Using the pulse radiolysis technique and specific radical scavengers, it has been shown that OH radicals react by H-abstraction (k = 3.7 × 109 dm3 mol-1 s-1), generating primary (4, ~45%) and tertiary (2, ~35%) α-alkoxyalkyl radicals as well as secondary and primary β-alkoxyalkyl radicals (3 and 1). In the absence of dioxygen, radicals 1-4 decay (2k = 1 × 109 dm3 mol-1 s-1) by recombination and disproportionation yielding dimers and vinyl ethers in nearly equal amounts. In the presence of dioxygen, four different peroxyl radicals (5-8) are formed. They decay bimolecularly by non-uniform kinetics (initially, 2k ≈ 7 × 107 dm3 mol-1 s-1). Especially at low dose rate, they also undergo (mainly) intramolecular H-abstraction. This leads to an increased autoxidation, e.g. dioxygen uptake reaches values more than three-times the initial radical yield. Based on these data, the major reaction pathways as well as some side- and consecutive reactions are discussed.
- Janik, Ireneusz,Ulanski, Piotr,Rosiak, Janusz M.,Von Sonntag, Clemens
-
p. 2034 - 2040
(2007/10/03)
-
- PalladiumdD-catalyzed exchange and isomerization reactions. 17. Exchange of chiral allyl alcohols with hydroxide, methoxide, and phenyl at high [Cl-]. Stereochemistry of the wacker reaction
-
At high [Cl ] (> 2.0 M), PdCl42- catalyzes the exchange of chiral allylic alcohols with hydroxy, methoxy, and phenyl to give chiral allyl-substituted olefins. With unsymmetrical olefins, isomerization occurs along with exchange. The hydroxyl exchange occurs in aqueous solution while the other exchanges are carried out in methanol solution. At low [Cl-] (0.1 M) oxidation to the corresponding β-hydroxy-, methoxy-, and phenyl-substituted carbonyl compounds occurred. The absolute configurations of the oxidation and exchange products should be the same if the same mode of addition to the Pd(II)-β-complex is operative. The absolute configurations of the oxidation and exchange products for the phenylation reaction were the same, while for hydroxy and methoxy they were different. This result indicates methanol and water must have different stereochemistries of addition at high and low [Cl-]. Thus, previous studies showing anti hydroxypalladation at high [Cl-] are not valid indicators of the stereochemistry at low [Cl-]. If anti addition occurs at high [Cl-], the addition must be syn at low [Cl-].
- Hamed, Othman,Henry, Patrick M.,Thompson, Charles
-
p. 7745 - 7750
(2007/10/03)
-
- DIASTEREO-DIFFERENTIATING CYCLOPROPANATION OF A CHIRAL ENOL ETHER: A SIMPLE METHOD FOR THE PREPARATION OF OPTICALLY PURE CYCLOPROPYL ETHERS
-
Enol ether of cyclohexanone carrying 2,4-pentanediol (PD) or 2,6-dimethyl-3,5-heptanediol (DMHD) as a chiral auxiliary was subjected to diastereo-differentiating cyclopropanation.The highest diastereomer excess (d.e.) of the product was found to be 95.2percent in the case of PD and over 99.5percent in the case of DMHD.The enol ethers prepared from various ketones and DMHD were also cyclopropanated in giving cyclopropyl ethers in almost 100percent d.e..
- Sugimura, Takashi,Yoshikawa, Masato,Futagawa, Tohru,Tai, Akira
-
p. 5955 - 5966
(2007/10/02)
-
- REACTION DES VINYLOGUES D'HEMIACETALS ET DE LEURS EQUIVALENTS SYNTHETIQUES SUR LES ETHERS D'ENOLS HETEROCYCLIQUES
-
We describe the reaction of hemiacetal vinylogs 2 or their synthetic equivalent with cyclic enol ethers 1 yielding ketoacetals 3.Acidic treatment of these compounds leads to bicyclic heterocycles 8 or enone aldehyde 12 depending on the nature of substituents R1.
- Poirier, Jean-Marie,Dujardin, Gilles
-
p. 3337 - 3340
(2007/10/02)
-
- VINYL MIGRATION IN THE OXYTHALLATION OF SOME 1,3-DIENES
-
The oxythallation of certain 1,3-dienes with thallium (III) nitrate trihydrate in MeOH-CH2Cl2 at 0-20 deg C gave products after vinyl migration .Methyl 1-methylcyclopropyl ketone, obtained in the reaction of 2,3-dimethyl-1,3-butadiene, was presumably derived from a cyclopropylmethyl cation, an intermediate in the vinyl migration.
- Murakami, Masashi,Nishida, Shinya
-
p. 997 - 1000
(2007/10/02)
-