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1.
Readily available chiral phosphoramidites are a promising class of ligands for nickel-catalyzed asymmetric hydrovinylation of vinyl arenes. Cooperative effects are operative when ligands with more than one element of chirality are used. Choosing the proper stereochemistry in each part of the modular ligand system leads to high chemoselectivities and excellent enantioselectivities up to 94%. Moreover, the catalysts derived from these ligands proved extremely efficient and remarkably robust performing up to 8300 catalytic turnovers at an initial turnover frequency beyond 1000 h-1. The large potential for structural variation and their straightforward synthesis make the phosphoramidites currently the best lead structure for catalyst development in this field. 相似文献
2.
A catalytic hydrovinylation of N-acetylenamines with ethylene is reported. This new hydrovinylation reaction is catalyzed by a ruthenium hydride complex, RuHCl(CO)(PCy(3))(2), providing a series of N-acetylamines with a quaternary carbon center with up to 99% yield. 相似文献
3.
The asymmetric hydrovinylation (1 mol % Ni-cat., 1 atm, ethylene, >98% ee) products from 1-methylenetetralines are readily converted into 3,3-disubstituted oxindoles and subsequently to pyrrolidinoindolines. These hydrovinylation products are also useful for the syntheses of enantiopure benzomorphans. 相似文献
4.
1-Alkylstyrenes undergo efficient hydrovinylation (coupling with ethylene) in the presence of 1 mol % of a Ni catalyst prepared from [(allyl)NiBr]2, Na+BAr4- (Ar = 3,5-bistrifluoromethylphenyl), and phosphoramidite ligands (derived from enantiopure binaphthols and 1-methylbenzylamines), giving hydrovinylation products in excellent yields and enantioselectivities. The products contain a quaternary center with two versatile latent functionalities, an arene and a vinyl group, useful for further synthetic elaborations. 相似文献
5.
Among the handful of monophosphine ligands that effect asymmetric hydrovinylation of vinylarenes, 2-diphenylphosphino-2'-methoxy-1,1'-binaphthyl (MOP) is among the most accessible. Addition of a methyl group at the 3'-position of this ligand significantly improves the enantioselectivity of hydrovinylation of prototypical alkenes. Introduction of a chiral phospholane at the C2 position of this scaffolding has no effect on the enantioselectivity. These results are consistent with a model proposed for the asymmetric induction for this exacting reaction. 相似文献
6.
Ahlquist M Fabrizi G Cacchi S Norrby PO 《Journal of the American Chemical Society》2006,128(39):12785-12793
The mechanism of the Pd-catalyzed hydroarylation and hydrovinylation reaction of alkynes has been studied by a combination of experimental and theoretical methods (B3LYP), with an emphasis on the phosphine-free version. The regioselectivity of the hydroarylation and hydrovinylation shows unexpected differences, which could be attributed mainly to the higher steric demand of the cyclohexenyl group as compared to the phenyl group. Hydroarylation of alpha,beta-acetylenic carbonyl substrates yields a very unusual anti-Michael selectivity, which is shown to result from reaction of the nonconjugated double bond, leaving the conjugation intact. In all cases were the regioselectivities reproduced by the calculations. 相似文献
7.
The first Ru-catalyzed enantioselective hydrovinylation has been realized by using an asymmetric counteranion-directed catalysis strategy. Styrene derivatives react with ethylene in excellent yields and promising enantioselectivity using this approach. 相似文献
8.
Only a limited number of ligands have been successfully employed for the Ni-catalyzed asymmetric hydrovinylation reaction. Diarylphosphonites prepared from readily available carbohydrates in conjunction with a highly dissociated counterion ([3,5-(CF3)2-C6H3)4B]- or SbF6-) effect the hydrovinylation of 4-bromostyrene or 4-isobutylstyrene under ambient pressure of ethylene with the best overall selectivities reported to date for these important substrates. In a prototypical synthesis of a 2-arylpropionic acid, 3-(4-bromophenyl)-1-butene (prepared in 98% isolated yield and 89% ee from 4-bromostyrene) has been transformed into (R)-ibuprofen by Ni-catalyzed cross-coupling with i-BuMgBr, ozonolysis, and subsequent oxidation of the resulting aldehyde. 相似文献
9.
Shi WJ Zhang Q Xie JH Zhu SF Hou GH Zhou QL 《Journal of the American Chemical Society》2006,128(9):2780-2781
The highly enantioselective hydrovinylation of alpha-alkyl vinylarenes was realized by using nickel complexes of chiral spiro phosphoramidite ligands. The method provided a new approach to the construction of chiral all-carbon quaternary centers. 相似文献
10.
The hydrovinylation reaction is a codimerization of a 1,3-diene or vinyl arene and ethene with great potential for fine chemicals and pharmaceuticals. For the first time, enantioselective cobalt-catalyzed hydrovinylations of styrene were achieved with a cobalt-based system bearing a chiral bis(phosphine)amide ligand. 相似文献
11.
[reaction: see text] A three-step, two-pot procedure involving asymmetric hydrovinylation followed by Suzuki-Miyaura reaction represents by far the shortest synthesis of this popular bisabolane. Other applications for the synthesis of similar compounds with chiral benzyl centers can be easily envisioned. 相似文献
12.
Asymmetric hydrovinylation of silyl-protected allylic alcohols catalyzed by nickel complexes of chiral spiro phosphoramidite ligands was developed. A series of homoallylic alcohols with a chiral quaternary center were produced in high yields (up to 97%) and high enantioselectivities (up to 95% ee). The reaction provides an efficient method for preparing bifunctional compounds with a chiral quaternary carbon center. 相似文献
13.
14.
Annulation of Alkynyl Aryl Ethers with Allyl Pivalates To Give 2,3‐Bismethylenechromanes through Double C−H Bond Cleavage 下载免费PDF全文
Dr. Yasunori Minami Megumi Sakai Tomohiro Anami Prof. Dr. Tamejiro Hiyama 《Angewandte Chemie (International ed. in English)》2016,55(30):8701-8705
The treatment of silylethynyloxyarenes with allylic pivalates in the presence of a palladium catalyst led to efficient C?H bond cleavage in both substrates and a novel annulation reaction to give 2,3‐bismethylenechromanes. When ortho‐allylated silylethynyloxybenzenes were used as the substrates, the same products were obtained. This result shows that site‐selective intramolecular hydrovinylation is involved in the annulation reaction. The synthetic utility of the products was demonstrated by the construction of condensed polycycles. 相似文献
15.
Eggeling EB Hovestad NJ Jastrzebski JT Vogt D van Koten G 《The Journal of organic chemistry》2000,65(26):8857-8865
Phosphino carboxylic acid ester terminated G(0) compounds Si(CH(2))(3)SiMe(2)(C(6)H(4)CH(2)OC(O)(CH(2))(n)()CH(2)PPh(2)(4) (9a and 9b; n = 1, 2) and the carbosilane dendrimers Si(CH(2))(3)Si((CH(2))(3)SiMe(2)(C(6)H(4)CH(2)OC(O)(CH(2))(n)()CH(2) PPh(2))(3)(4) (10a and 10b; n = 1, 2) have been prepared as hemilabile nanoscale ligands for the palladium-catalyzed codimerization of olefins. The hydrovinylation of styrene was carried out in a continuously operated nanofiltration membrane reactor. Under continuous conditions, the selectivity of the reaction is increased considerably. Monomeric model complexes and the dendritic catalysts were compared for their activity and selectivity in batch reactions. The Pd catalyst complexes were prepared in situ from the dendritic ligands and an (allyl)palladium(II) precursor. 相似文献
16.
17.
Fine tuning of the biaryl and amino moieties of Feringa's phosphoramidite ligands yields structurally simpler, yet more efficient and selective, ligands for asymmetric hydrovinylation of vinylarenes and acylic 1,3-dienes. The enantioselectivities and yields observed in the formation of the 3-arylbutenes are among the highest for all asymmetric catalytic processes reported to date for the synthesis of intermediates for the widely used antiinflammatory 2-arylpropionic acids including naproxen, ibuprofen, fenoprofen, and flurbiprofen. 相似文献
18.
The coordinated ethylene molecule in the dicationic complex [(PNP)Pt(CH2=CH2)](BF4)2 (PNP = 2,6-bis(diphenylphosphinomethyl)pyridine) undergoes nucleophilic attack by free internal alkenes, giving the isolable complexes [(PNP)Pt(CH2=CHCH(Me)CMeRR'](BF4)2 (R, R' = H, Me) and providing a new effective pathway for a chemo- and regio-selective catalytic hydrovinylation reaction. 相似文献
19.
[reaction: see text] Norbornene undergoes Ni-catalyzed (1-2 mol% allylnickel bromide/phosphine/NaBARF or AgSbF(6), 1 bar ethylene, -50 degrees C) hydrovinylation (>97% yield), giving either a 1:1 or a 2:1 (norbornene/ethylene) adduct depending on the size of the phosphine. Use of binaphthol-derived phosphoramidite ligand results in up to 80% ee for the 1:1 adduct. The course of the reaction is highly dependent on the ligand (size and configuration of the appendages) and the counteranion present. 相似文献
20.
1,3-Dienes derived from steroidal D-ring C 17-ketones undergo Ni(II)-catalyzed hydrovinylation to give 1,2- or 1,4-addition of ethylene. Using finely tuned phosphoramidite ligands, it is possible to synthesize either the C 20 ( R)- or ( S)-derivatives without mutual contamination. The proportion of the 1,4-adduct, which is also formed stereoselectively, can be minimized by optimizing the reaction conditions. Because the two alkenes in the resultant dienes have differing steric demands for many potential reactions, and are ideally juxtaposed for further D-ring functionalization, these intermediates could be useful for the preparation of biologically important compounds such as vitamin D analogs and various antitumor steroidal glycosides. 相似文献