486413-41-6Relevant academic research and scientific papers
Manganese Catalyzed Enantioselective Epoxidation of α,β-Unsaturated Amides with H2O2
Ottenbacher, Roman V.,Kurganskiy, Vladimir I.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
, p. 2778 - 2782 (2021/04/29)
Herewith, we report the enantioselective epoxidation of electron-deficient cis- and trans-α,β-unsaturated amides with the environmentally benign oxidant H2O2. The catalysts - manganese complexes with bis-amino-bis-pyridine and structurally related ligands - exhibit reasonably high efficiency (up to 100 TON) and excellent chemo- and enantioselectivity (up to 100% and 99% ee, respectively). Crucially, the cis-enamides epoxidation enantioselectivity and yield are dramatically enhanced by the presence of NH-moiety, which effect can be explained by the hydrogen bonding interaction between the cis-enamide substrate and the manganese based oxygen transferring species. (Figure presented.).
Enantioselective Epoxidation of Electron-Deficient Alkenes Catalyzed by Manganese Complexes with Chiral N4 Ligands Derived from Rigid Chiral Diamines
Chen, Xiangning,Gao, Bao,Su, Yijin,Huang, Hanmin
supporting information, p. 2535 - 2541 (2017/08/16)
A series of tetradentate sp2N/sp3N hybrid chiral N4 ligands derived from rigid chiral diamines were synthesized, which enabled the first manganese-catalyzed enantioselective epoxidation of electron-deficient alkenes with hydrogen peroxide (H2O2) as an oxidant. The reaction furnishes enantiomerically pure epoxy amides, epoxy ketones as well as epoxy esters in good yields and excellent enantioselectivities (up to 99.9% ee) with lower catalyst loading. Preliminary studies on structure–activity relationship demonstrated that maintaining comparatively lower electron-donating ability of the sp3N and relatively higher electron-donating ability of sp2N of the N4 ligands is beneficial to getting higher activity and selectivity, thus providing us a new view to understand epoxidation with H2O2. (Figure presented.).
Dynamic ligand exchange of the lanthanide complex leading to structural and functional transformation: One-pot sequential catalytic asymmetric epoxidation-regioselective epoxide-opening process
Tosaki, Shin-Ya,Tsuji, Riichiro,Ohshima, Takashi,Shibasaki, Masakatsu
, p. 2147 - 2155 (2007/10/03)
The characteristic property of the lanthanide complex, which easily undergoes a dynamic ligand exchange and alters its structure and function in situ, is described. After the completion of the catalytic asymmetric epoxidation of various α,β-unsaturated amides 2 in the presence of the Sm-(S)-BINOL-Ph3-As=O (1:1:1) complex 1 (2-10 mol %), the addition of Me3SiN3 directly to the reaction mixture led to smooth epoxide-opening at room temperature, affording the corresponding anti-β-azido-α-hydroxyamide 4 in excellent overall yield (up to 99%) with complete regioselectivity and excellent enantiomeric excess (up to >99%). The key to the success of the sequential process was the in situ generation of the highly reactive samarium azide complex through dynamic ligand exchange. In situ IR spectroscopy and other experiments provided strong evidence that the samarium azide complex was generated. In addition, the relatively high Lewis basicity of the amide moiety had a key role in the high reactivity of both the epoxidation and the epoxide-opening reactions. Examinations of other nucleophiles such as sulfur or carbon nucleophiles as well as transformations of epoxide-opened products are also described.
Efficient Synthesis of Chiral α- and β-Hydroxy Amides: Application to the Synthesis of (R)-Fluoxetine
Kakei, Hiroyuki,Nemoto, Tetsuhiro,Ohshima, Takashi,Shibasaki, Masakatsu
, p. 317 - 320 (2007/10/03)
Four flavors for epoxide openings: The regioselective openings of epoxy amides obtained by asymmetric epoxidation yields all types of aryl- and alkyl-substituted hydroxy amides sometimes counter to the reactivity of the α- and β-positions.
Catalytic asymmetric epoxidation of α,β-unsaturated carboxylic acid imidazolides and amides by lanthanide-BINOL complexes
Ohshima, Takashi,Nemoto, Tetsuhiro,Tosaki, Shin-Ya,Kakei, Hiroyuki,Gnanadesikan, Vijay,Shibasaki, Masakatsu
, p. 10485 - 10497 (2007/10/03)
Highly enantioselective catalytic asymmetric epoxidation of α,β-unsaturated carboxylic acid imidazolides and simple amides was developed. In the presence of 5-10mol% of lanthanide-BINOL complexes, the reaction proceeded smoothly with high substrate generality. In particular, in the cases of α,β-unsaturated amides, there was nearly perfect enantioselectivity (>99% ee). The corresponding epoxides were successfully transformed into many types of useful chiral compounds such as α,β-epoxy esters, α,β-epoxy amides, α,β-epoxy aldehydes, α,β-epoxy β-keto ester, and α- and β-hydroxy carbonyl compounds. B3LYP density functional studies were performed to predict substrate reactivity.
Catalytic asymmetric epoxidation of α,β-unsaturated amides: Efficient synthesis of β-aryl α-hydroxy amides using a one-pot tandem catalytic asymmetric epoxidation - Pd-catalyzed epoxide opening process
Nemoto, Tetsuhiro,Kakei, Hiroyuki,Gnanadesikan, Vijay,Tosaki, Shin-Ya,Ohshima, Takashi,Shibasaki, Masakatsu
, p. 14544 - 14545 (2007/10/03)
The catalytic asymmetric epoxidation of α,β-unsaturated amides using Sm-BINOL-Ph3As=O complex was succeeded. Using 5-10 mol % of the asymmetric catalyst, a variety of amides were epoxidized efficiently, yielding the corresponding α,β-epoxy amides in up to 99% yield and in more than 99% ee. Moreover, the novel one-pot tandem process, one-pot tandem catalytic asymmetric epoxidation-Pd-catalyzed epoxide opening process, was developed. This method was successfully utilized for the efficient synthesis of β-aryl α-hydroxy amides, including β-aryllactyl-leucine methyl esters. Interestingly, it was found that beneficial modifications on the Pd catalyst were achieved by the constituents of the first epoxidation, producing a more suitable catalyst for the Pd-catalyzed epoxide opening reaction in terms of chemoselectivity. Copyright
