- Stereoselective synthesis of (Z)-1-alkylseleno-1-alkenes by Ni-catalyzed coupling reaction of (Z)-dialkylselenoethenes with organozinc halides
-
(Z)-Dialkylselenoethenes 2, prepared conveniently from the hydrozirconation of dialkylselenoacetylenes 1 with Cp2Zr (H)Cl in THF followed by protonolysis, react readily at -10°C in THF with organozinc halides in the presence of a catalytic amou
- Huang, Xian,Sun, Ai Ming
-
-
Read Online
- Chemo- and regioselective reductive transposition of allylic alcohol derivatives via iridium or rhodium catalysis
-
We report highly chemo- and regioselective reductive transpositions of methyl carbonates to furnish olefin products with complementary regioselectivity to that of established Pd-catalysis. These Rh- and Ir-catalysed transformations proceed under mild conditions and enable selective deoxygenation in the presence of functional groups that are susceptible to reduction by metal hydrides.
- Lundgren, Rylan J.,Thomas, Bryce N.
-
supporting information
p. 958 - 961
(2016/01/20)
-
- Ligand Control of E/Z Selectivity in Nickel-Catalyzed Transfer Hydrogenative Alkyne Semireduction
-
A nickel-catalyzed transfer hydrogenative alkyne semireduction protocol that can be applied to both internal and terminal alkynes using formic acid and Zn as the terminal reductants has been developed. In the case of internal alkynes, the (E)- or (Z)-olefin isomer can be accessed selectively under the same reaction conditions by judicious inclusion of a triphos ligand.
- Richmond, Edward,Moran, Joseph
-
p. 6922 - 6929
(2015/10/05)
-
- Convenient transfer semihydrogenation methodology for alkynes using a PdII-NHC precatalyst
-
A convenient and easy-to-use protocol for the Z-selective transfer semihydrogenation of alkynes was developed, using ammonium formate as the hydrogen source and the easily prepared and commercially available, highly stable complex PdCl(η3-C3H5)(IMes) (1) as the (pre)catalyst. Combined with triphenyl posphine as an additional ligand, this system provides a robust catalytic synthetic method that shows little to no over-reduction or isomerization after full substrate conversion. The system allows the direct use of solvents and reagents, as received from the supplier without drying or purification, thus providing a practical method for semihydrogenation of a broad range of alkynes. The mechanism behind these high and enhanced selectivities was determined through a set of kinetic experiments.
- Drost, Ruben M.,Bouwens, Tessel,Van Leest, Nicolaas P.,De Bruin, Bas,Elsevier, Cornelis J.
-
p. 1349 - 1357
(2014/05/20)
-
- Bidentate hydroxyalkyl NHC ligands for the copper-catalyzed asymmetric allylic substitution of allyl phosphates with grignard reagents
-
Demonstrating their potential: Bidentate alkoxy NHC ligands have been used in the copper-catalyzed asymmetric allylic alkylation of allyl phosphates with Grignard reagents (see scheme). The method provides access to tertiary and quaternary chiral centers with high regio- and enantioselectivity. The system is also applied to the synthesis of chiral E,E-dienes, a key structural motif prevalent in natural products. Copyright
- Magrez, Magaly,Le Guen, Yann,Basle, Olivier,Crevisy, Christophe,Mauduit, Marc
-
supporting information
p. 1199 - 1203
(2013/02/25)
-
- Iron-catalysed, hydride-mediated reductive cross-coupling of vinyl halides and Grignard reagents
-
An iron-catalysed, hydride-mediated reductive cross-coupling reaction has been developed for the preparation of alkanes. Using a bench-stable iron(ii) pre-catalyst, reductive cross-coupling of vinyl iodides, bromides and chlorides with aryl- and alkyl Grignard reagents successfully gave the products of formal sp3-sp3 cross-coupling reactions.
- Le Bailly, Bryden A. F.,Greenhalgh, Mark D.,Thomas, Stephen P.
-
supporting information; experimental part
p. 1580 - 1582
(2012/03/26)
-
- Amphoteric α-boryl aldehydes
-
A new class of stable molecules, α-boryl aldehydes, has been prepared from oxiranyl N-methyliminodiacetyl boronates by a 1,2-boryl migration with concomitant epoxide scission. A range of boryl imines, alkenes, alcohols, acids, enol ethers, enamides, and other functionalized boronic acid derivatives that are difficult or impossible to prepare using established protocols can be accessed from α-boryl aldehydes. The chemoselective transformations of these building blocks, including the facile synthesis of functionalized unnatural amino acids from silyloxy and amido vinyl boronates, attest to the potential of α-boryl aldehydes in chemical synthesis.
- He, Zhi,Yudin, Andrei K.
-
supporting information; experimental part
p. 13770 - 13773
(2011/10/05)
-
- Palladium-catalyzed allyl cross-coupling reactions with in situ generated organoindium reagents
-
Inter- and intramolecular palladium-catalyzed allyl cross-coupling reactions, using allylindium generated in situ from allyl halides and indium, is demonstrated. Allylindium compounds may be effective nucleophilic coupling partners in palladium-catalyzed cross-coupling reactions. A variety of allyl halides, such as allyl iodide, allyl bromide, crotyl bromide, prenyl bromide, geranyl bromide, and 3-bromocyclohexene afforded the allylic cross-coupling products in good to excellent yields. Stereochemistry of the double bond is retained in the allylic cross-coupling reactions. Electrophilic cross-coupling partners, such as aryl and vinyl halides, dibromoolefin, alkynyl iodide, and aryl and vinyl triflates participate in these reactions. The presence of various substituents, such as n-butyl, ketal, acetyl, ethoxycarbonyl, nitrile, N-phenylamido, nitro, and chloride groups on the aromatic ring of electrophilic coupling partners showed little effect on the efficiency of the reactions. The present conditions work equally well for not only intermolecular but also intramolecular palladium-catalyzed cross-coupling reactions. These methods provide an efficient synthetic method for the introduction of an allyl group, which can be easily further functionalized to afford an sp2- and sp-hybridized carbon. The present method complements existing synthetic methods as a result of advantageous features such as easy preparation and handling, thermal stability, high reactivity and selectivity, operational simplicity, and low toxicity of allylindium reagents.
- Lee, Kooyeon,Kim, Hyunseok,Mo, Juntae,Lee, Phil Ho
-
scheme or table
p. 2147 - 2157
(2011/10/31)
-
- New method for cycloalumination of disubstituted acetylenes with 1,2-dichloroethane
-
A new procedure has been developed for the synthesis of 2,3-dialkyl(phenyl)aluminacyclopent-2-enes by Cp2TiCl 2-catalyzed cycloalumination of disubstituted acetylenes with EtAlCl2 in the presence of ethylene generated in situ from 1,2-dichloroethane and activated magnesium.
- Ramazanov,Ibragimov,Dzhemilev
-
scheme or table
p. 781 - 784
(2009/06/28)
-
- Cross-coupling reaction of allylic and benzylic carbonates with organo[2-(hydroxymethyl)phenyl]dimethylsilanes
-
The title reaction is found to proceed in the presence of a palladium catalyst and in the absence of any activator. Various functional groups are tolerated to give a diverse range of 1,4-diene and diarylmethane products, which are ubiquitous units of natural products and pharmaceuticals. Copyright
- Nakao, Yoshiaki,Ebata, Shiro,Chen, Jinshui,Imanaka, Hidekazu,Hiyama, Tamejiro
-
p. 606 - 607
(2008/02/07)
-
- Reactions of polymer-supported α-selenoaldehydes with Grignard regents. A facile solid-phase stereoselective synthesis of (E)-1,2-disubstituted ethenes
-
Polymer-supported α-selenoaldehydes easily obtained by reaction of polymer-supported 4-(phenyl-seleno)morpholine with aldehydes react with Grignard reagents to form polymer-supported β-hydroxyalkyl selenides, which were treated with thionyl chloride/triethylamine leading to (E)-1,2-disubstituted ethenes in good yields.
- Sheng, Shou-Ri,Huang, Xian
-
p. 893 - 896
(2007/10/03)
-
- Highly efficient allyl cross-coupling reactions of allylindiums with organic electrophiles
-
This paper describes highly efficient allyl cross-coupling reactions of allylindiums with organic electrophiles such as aryl and vinyl triflates, vinyl halides, dibromoolefin, and alkynyl iodide. The reactions were carried out using 4 mol % Pd(PPh3)4 in the presence of 3 equiv of LiCl in DMF at 100 °C under a nitrogen atmosphere. Allylindium, generated from the reaction of 1 equiv of indium with 1.5 equiv of allyl halide, gave the best result as a coupling partner. The present method is mild and simple to apply, and it produces a diverse range of allylic compounds in good to excellent yields.
- Lee, Kooyeon,Lee, Jinsung,Lee, Phil Ho
-
p. 8265 - 8268
(2007/10/03)
-
- Stereoselective synthesis of 1,4-dienes by chelation-controlled reduction of benzothiazole β-oxosulfides
-
Allylated β-oxosulfides of benzothiazole can replace β-oxophosphane oxides to provide a stereospecific alkene synthesis. These sulfides, by reduction with sodium borohydride afford predominantly syn β-hydroxy sulfides. DIBAL reduction in the presence of magnesium bromide improves the syn stereomer formation. Base treatment of these β-hydroxy sulfides affords (Z)-allyl thiiranes which are converted into (E, Z)-dienes.
- Calo, Vincenzo,Nacci, Angelo
-
p. 3825 - 3828
(2007/10/03)
-
- Stereoselective dehalogenation of (Z)-1-halo-1-alkenyldialkylborane with tributyltin hydride: The behavior of tributyltin hydride as a hydride donor
-
The reaction of (Z)-1-halo-1-alkenyldialkylborane (1) with tributyltin hydride (n-Bu3SnH) at 0°C or room temperature results in reductive removal of the halogen atom to afford (E)- or (Z)-1-alkenyldialkylborane whose stereochemistry depends on the dialkylboryl group and the alkenyl group of 1.
- Hoshi, Masayuki,Takahata, Kimitomo,Arase, Akira
-
p. 453 - 456
(2007/10/03)
-
- Efficient Conditions for the Palladium(II) Mediated Coupling of Organostannanes: The Synthesis of 1,3-Dienes, 1,4-Dienes, 1,3-Diynes and Biphenyls
-
Convenient conditions are described for the preparation of 1,3-dienes by vinylstannane homocoupling using palladium(II)-catalysis with oxygen (or air) for Pd(0)/Pd(II) reoxidation; related homo-couplings, and cross-coupling reactions with allylstannane, are used to obtain 1,3-diynes, biaryls and 1,4-dienes.
- Alcaraz, Lilian,Taylor, Richard J. K.
-
p. 791 - 792
(2007/10/03)
-
- Aminium Salts Induced Desulphurization of Allyl and Diallyl Thiiranes. Synthesis of Dienes and Trienes
-
Catalytic amounts of aminium salts A-B induce the conversion of methylene chloride in solutions of several allyl and diallyl episulphides 1-6 into the corresponding unsaturated derivatives 7-12.The desulphurization process, which occurs through a plausible chain electron-transfer mechanism, rapid and may proceed in a fashion that preserves the stereochemistry of the starting episulphide.
- Calo, Vincenzo,Lopez, Luigi,Nacci, Angelo,Mele, Giuseppe
-
p. 8935 - 8940
(2007/10/02)
-
- Alkylation of Allylic Derivatives. 14. Relationship of Double-Bond Configuration between Reactant and Product for Cross-Coupling Reactions of Z-Allylic Carboxylates with Organocopper Reagents
-
Cross-coupling reactions of alkylcuprates (sp3 reagents) with allylic carboxylates can result in loss of double-bond configuration in the α-alkylation product.Loss of configuration occurs during the reaction, which shows that an intermediate is involved in which the double bond is temporarily relocated.With phenyl- and vinylcuprates (sp2 reagents) the original double-bond configuration is fully preserved in all cases.This shows that the original double bond is partly retained throughout the reaction.Evidently with sp2 reagents, oxidative addition leads directly to a ?-allylcopper(III) complex (12).
- Underiner, Ted L.,Paisley, Steven D.,Schmitter, Joel,Lesheski, Larry,Goering, Harlan L.
-
p. 2369 - 2374
(2007/10/02)
-
- Palladium Catalyzed Reactions of Organic Halides with Organotin Compounds Involving Insertion of Norbornene. Synthesis of 2,3-Disubstituted Norbornane
-
2,3-Disubstituted norbornanes were prepared by the palladium catalyzed reaction of a ternary system composed of organic halide, organotin compound, and norbornene.Aryl and vinyl bromides, and acyl chloride were good substrates, but benzyl and allyl chlorides were not.Vinyl, phenyl, ethynyl, and allyltin compounds were utilizable reagents.
- Kosugi, Masanori,Tamura, Hiroyuki,Sano, Hiroshi,Migita, Toshihiko
-
p. 193 - 194
(2007/10/02)
-
- HIGHLY CHEMOSELECTIVE COUPLING REACTIONS OF ORGANOVANADIUM COMPOUNDS
-
Organovanadium compounds generated in dichloromethane from equimolar amounts of vanadium trichloride and Grignard reagents underwent the chemoselective cross-coupling reaction with acid chlorides leading to the corresponding ketones.Treatment with allyl halides resulted in allylation of organovanadium compounds.In the case of propargyl bromide, regioselective displacement occured to produce allene derivatives.
- Hirao, Toshikazu,Misu, Daisuke,Yao, Koichi,Agawa, Toshio
-
p. 929 - 932
(2007/10/02)
-
- THE ADDITION OF CUPRATES TO VINYLTRIPHENYLPHOSPHONIUM BROMIDE: A SYNTHESIS OF 1,5-DISUBSTITUTED Z,Z-PENTA-1,4-DIENES
-
It is shown that alkyl, alkenyl and aryl cuprates add to vinyltriphenylphosphonium bromide to provide phosphoranes and that the Z:E ratio of their Wittig condensation products with benzaldehyde and hexanal are strongly influenced by the addition of hexame
- Just, George,O'Connor, Brian
-
p. 1799 - 1802
(2007/10/02)
-