54899-45-5Relevant articles and documents
1,4-Bis-Dipp/Mes-1,2,4-Triazolylidenes: Carbene Catalysts That Efficiently Overcome Steric Hindrance in the Redox Esterification of α- And β-Substituted α,β-Enals
Yatham, Veera Reddy,Harnying, Wacharee,Kootz, Darius,Neud?rfl, J?rg-M.,Schl?rer, Nils E.,Berkessel, Albrecht
, p. 2670 - 2677 (2016/03/12)
As reported by Scheidt and Bode in 2005, sterically nonencumbered α,β-enals are readily converted to saturated esters in the presence of alcohols and N-heterocyclic carbene catalysts, e.g., benzimidazolylidenes or triazolylidenes. However, substituents at the α- or β-position of the α,β-enal substrate are typically not tolerated, thus severely limiting the substrate spectrum. On the basis of our earlier mechanistic studies, a set of N-Mes- or N-Dipp-substituted 1,2,4-triazolium salts were synthesized and evaluated as (pre)catalysts in the redox esterification of various α- or β-substituted enals. In particular the 1,4-bis-Mes/Dipp-1,2,4-triazolylidenes overcome the above limitations and efficiently catalyze the redox esterification of a whole series of α/β-substituted enals hitherto not amenable to NHC-catalyzed transformations. The synthetic value of 1,4-bis-Mes/Dipp-1,2,4-triazolylidenes is further demonstrated by the one-step bicyclization of 10-oxocitral to (racemic) nepetalactone in diastereomerically pure form.
Hydroalkylation of Alkenes Using Alkyl Iodides and Hantzsch Ester under Palladium/Light System
Sumino, Shuhei,Ryu, Ilhyong
supporting information, p. 52 - 55 (2016/01/12)
The hydroalkylation of alkenes using alkyl iodides with Hantzsch ester as a hydrogen source occurred smoothly under a Pd/light system, in a novel, tin-free Giese reaction. A chemoselective reaction at C(sp3)-I in the presence of a C(sp2)-X (X = Br or I) bond was attained, which allowed for the stepwise functionalization of two types of C-X bonds in a one-pot procedure.
Pd-Catalyzed Regioselective Alkoxycarbonylation of 1-Alkenes Using a Lewis Acid [SnCl2 or Ti(OiPr)4] and a Phosphine
Amézquita-Valencia, Manuel,Achonduh, George,Alper, Howard
, p. 6419 - 6424 (2015/06/30)
The phosphine ligand mediated palladium catalyzed alkoxycarbonylation of alkenes was investigated with the objective of attaining good linear selectivity for the ester. The effect of various parameters such as solvents, additives, palladium precursors, CO pressures, and alkenes of various structural complexities were examined. The results revealed the importance of using a Lewis acid such as SnCl2 or Ti(OiPr)4 in combination with a monodentate ligand such CYTOP 292 or P(p-anisyl)3 to enhance the regioselectivity for the linear isomers in the range of 70-96%.
Inter- and intramolecular radical couplings of ene-ynes or halo-alkenes promoted by an InCl3/MeONa/Ph2SiH2 system
Hayashi, Naoki,Shibata, Ikuya,Baba, Akio
, p. 3093 - 3096 (2007/10/03)
(Chemical Equation Presented) An effective generation of indium hydride (HInCl2) under nonacidic conditions is achieved by transmetalation between Ph2SiH2 and InCl2OMe. The presented system achieves the titled coupling reactions in a radical manner. In particular, the nonacidic character enables the applications to acid-sensitive inter- and intramolecular ene-yne couplings.
Indium(III) chloride-sodium borohydride system: A convenient radical reagent for an alternative to tributyltin hydride system
Inoue, Katsuyuki,Sawada, Akemi,Shibata, Ikuya,Baba, Akio
, p. 906 - 907 (2007/10/03)
The indium hydride generated from NaBH4 and InCl3, is a promising candidate of alternative to Bu3SnH. In particular, the catalytic performance of InCl3 in the dehalogenation of alkyl and aryl halides, intramolecular cyclization and intermolecular coupling reaction are noteworthy. Copyright
A New Coupling Reaction of Alkyl Iodides with Electron Deficient Alkenes Nickel Boride (cat.) - Borohydride Exchange Resin in Methanol
Sim, Tae Bo,Choi, Jaesung,Joung, Meyoung Ju,Yoon, Nung Min
, p. 2357 - 2361 (2007/10/03)
The radical addition reaction of alkyl iodides with α,β-unsaturated esters, nitriles, and ketones proceeds in moderate to excellent yields (50-95%) using Ni(OAc)2 (0.05-0.2 equiv) - BER (3-5 equiv) in methanol in 1-9 h at room temperature or at 65°C. Nickel boride on borohydride exchange resin (BER) is a good alternative reagent to tributyltin hydride for the coupling of alkyl iodides with the electron deficient alkenes in methanol. Compared with tributyltin hydride method, this method has an advantage of simple workup, since nickel boride - BER can be removed readily by filtration.
A new coupling reaction of alkyl iodides with α,β-unsaturated esters using Ni2B(cat.)-BER in methanol
Sim, Tae Bo,Choi, Jaesung,Yoon, Nung Min
, p. 3137 - 3140 (2007/10/03)
Alkyl iodides can be coupled with α,β-unsaturated esters using Ni2B(0.05-0.2 eq)-BER(3 eq) in methanol at room temperature. Products (68-95%) are conveniently isolated, simply filtering the resin and evaporating the excess enoates and methanol.
PHOSPHINE NICKEL COMPLEX AS CATALYST IN REACTIONS OF ORGANIC BROMIDES RBr WITH α,β-UNSATURATED KETONES, NITRILES, AND ESTERS. CONJUGATE ADDITION OF R GROUP AND H ATOM ACROSS THE C=C BOND
Lebedev, S. A.,Lopatina, V. S.,Petrov, E. S.
, p. 444 - 446 (2007/10/03)
Reactions of organic bromides, particularly of secondary and tertiary alkyl bromides, with α,β - unsaturated carbonyl compounds and acrylonitryle in the presence of the catalytic system nickel complex-zinc result in formation of products of conjugate addition of the organic moiety of the bromide and a hydrogen atom across the C=C double bond of the unsaturated substrate.
Chromium(II)-Mediated Intermolecular Free-Radical Carbon-Carbon Bond Formation
Tashtoush, Hasan I.,Sustmann, Reiner
, p. 287 - 289 (2007/10/02)
Chromium(II) complexes are found to be effective mediators for intermolecular free-radical C-C bond formation.Thus, Cr(en)2(2+) species react with alkyl halides to generate the corresponding alkyl radicals which are readily trapped with electron-deficient alkenes to afford the coupling products.Key Words: Radicals / Bond formation, C-C / Chromium(II) complexes
13C Chemical Shift Non-Equivalence in Methylene Carbons of Monosubstituted Cyclohexanes
Ito, Hiroshi,Renaldo, Alfred F.,Johnson, Robert D.,Ueda, Mitsuru
, p. 273 - 276 (2007/10/02)
Monosubstituted cyclohexanes were synthesized by addition of a cyclohexyl radical to olefins bearing different substituents at the α-position.Six distinct methylene 13C resonances were observed, indicating that the methylene carbons located at the 2 and 6 positions and at 3 and 5 positions are not magnetically equivalent.This magnetic non-equivalence (anisochronism) observed in the monosubstituted cyclohexanes is due to the introduction of an asymmetric center β to the prochiral C-1 ring carbon atom. KEY WORDS Anisochronism Magnetic non-equivalence Cyclohexyl adducts Mercury method
