1674-30-2Relevant academic research and scientific papers
In Situ Formation and Reactions of Chloromethyl-lithium under Sonochemical Conditions
Einhorn, Cathy,Allavena, Corinne,Luche, Jean-Louis
, p. 333 - 334 (1988)
Under sonication, bromochloromethane, a carbonyl compound, and lithium in tetrahydrofuran yield the corresponding α-chlorohydrin, which can cyclise to the epoxide, in excellent yields.
Catalytic Meerwein-Pondorf-Verley reduction by simple aluminum complexes
Campbell, E. Joseph,Zhou, Hongying,Nguyen, SonBinh T.
, p. 2391 - 2393 (2001)
(matrix presented) Catalytic MPV reduction was successfully carried out using simple aluminum precatalysts. Alkylaluminum reagents were converted to a low-aggregation aluminum alkoxide that was highly active for the MPV reduction of several carbonyl substrates in high yield (50-99%) using iPrOH as the reducing agent. A high degree of cisftrans selectivity was achieved in the reduction of 2-methylcyclohexanone (cis/trans = 20/80) by iPrOH. When chiral hydride sources were utilized in the reduction of 2-chloroacetophenone, high enantioselectivity (68-80% ee) was observed.
Dihydroxylation of styrene by sodium chlorite with scandium triflate
Ohkubo, Kei,Hirose, Kensaku,Shibata, Takekatsu,Takamori, Kiyoto,Fukuzumi, Shunichi
, (2017)
Dihydroxylation of styrene by chlorite (ClO2 ?) with scandium triflate [Sc(OTf)3] occurs efficiently to produce 1-phenylethane-1,2-diol under the ambient conditions. Scandium triflate acting as a strong Lewis acid is found to accelerate the disproportionation of ClO2 ? to produce ClO? and ClO3 ?. A scandium-chlorine dioxide complex (Sc3+ClO2 ?) is generated by the reaction of ClO? with ClO2 ? in the presence of Sc3 +. The binding of Sc3 + to ClO2 ? was detected by the electron paramagnetic resonance measurements, enhancing the reactivity and selectivity of styrene hydroxylation.
Enantioselective ring-opening of epoxides by HF-reagents: Asymmetric synthesis of fluoro lactones
Haufe, Günter,Bruns, Stefan,Runge, Martina
, p. 55 - 61 (2001)
The asymmetric ring opening of meso- and racemic-epoxides with different HF-reagents mediated by enantiopure (salen)chromium chloride provides optically active fluorohydrins with maximum 90% e.e. This reaction as well as lipase-catalyzed deracemization of
A phosphonium ylide as a visible light organophotoredox catalyst
Toda, Yasunori,Tanaka, Katsumi,Matsuda, Riki,Sakamoto, Tomoyuki,Katsumi, Shiho,Shimizu, Masahiro,Ito, Fuyuki,Suga, Hiroyuki
supporting information, p. 3591 - 3594 (2021/04/14)
A phosphonium ylide-based visible light organophotoredox catalyst has been designed and successfully applied to halohydrin synthesis using trichloroacetonitrile and epoxides. An oxidative quenching cycle by the ylide catalyst was established, which was confirmed by experimental mechanistic studies.
Chiral aminoalcohols and squaric acid amides as ligands for asymmetric borane reduction of ketones: Insight to in situ formed catalytic system by DOSY and multinuclear NMR experiments
Dobrikov, Georgi M.,Nikolova, Yana,Petkova, Zhanina,Shestakova, Pavletta
supporting information, (2021/11/27)
A series of squaric acid amides (synthesized in 66–99% isolated yields) and a set of chiral aminoalcohols were comparatively studied as ligands in a model reaction of reduction of α-chloroacetophenone with BH3?SMe2. In all cases, the aminoalcohols demonstrated better efficiency (up to 94% ee), while only poor asymmetric induction was achieved with the corresponding squaramides. A mechanistic insight on the in situ formation and stability at room temperature of intermediates generated from ligands and borane as possible precursors of the oxazaborolidine-based catalytic system has been obtained by1H DOSY and multinuclear 1D and 2D (1H,10/11B,13C,15N) NMR spectroscopy of equimolar mixtures of borane and selected ligands. These results contribute to better understanding the complexity of the processes occurring in the reaction mixture prior to the possible oxazaborolidine formation, which play a crucial role on the degree of enantioselectivity achieved in the borane reduction of α-chloroacetophenone.
Dynamic Kinetic Resolution of Alcohols by Enantioselective Silylation Enabled by Two Orthogonal Transition-Metal Catalysts
Oestreich, Martin,Seliger, Jan
supporting information, p. 247 - 251 (2020/10/29)
A nonenzymatic dynamic kinetic resolution of acyclic and cyclic benzylic alcohols is reported. The approach merges rapid transition-metal-catalyzed alcohol racemization and enantioselective Cu-H-catalyzed dehydrogenative Si-O coupling of alcohols and hydrosilanes. The catalytic processes are orthogonal, and the racemization catalyst does not promote any background reactions such as the racemization of the silyl ether and its unselective formation. Often-used ruthenium half-sandwich complexes are not suitable but a bifunctional ruthenium pincer complex perfectly fulfills this purpose. By this, enantioselective silylation of racemic alcohol mixtures is achieved in high yields and with good levels of enantioselection.
CeO2-nanocubes as efficient and selective catalysts for the hydroboration of carbonyl groups
Bhawar, Ramesh,Bose, Shubhankar Kumar,Patil, Kiran S.
, p. 15028 - 15034 (2021/09/04)
The CeO2-nanoparticle catalysed hydroboration of carbonyl compounds with HBpin (pin = OCMe2CMe2O) is reported to afford the corresponding borate esters in excellent yield. A series of aromatic and aliphatic aldehydes and ketones having synthetically important functional groups were well-Tolerated under mild reaction conditions. Further, chemoselective hydroboration of aldehydes over other reducible functional groups such as ketone, nitrile, hydroxide, alkene, alkyne, amide, ester, nitro, and halides was achieved. Importantly the catalyst can be recycled up to ten runs with slight loss in activity. This journal is
Lipase mediated enzymatic kinetic resolution of phenylethyl halohydrins acetates: A case of study and rationalization
Fonseca, Thiago de Sousa,Vega, Kimberly Benedetti,da Silva, Marcos Reinaldo,de Oliveira, Maria da Concei??o Ferreira,de Lemos, Telma Leda Gomes,Contente, Martina Letizia,Molinari, Francesco,Cespugli, Marco,Fortuna, Sara,Gardossi, Lucia,de Mattos, Marcos Carlos
, (2020/02/18)
Racemic phenylethyl halohydrins acetates containing several groups attached to the aromatic ring were resolved via hydrolysis reaction in the presence of lipase B from Candida antarctica (Novozym 435). In all cases, the kinetic resolution was highly selective (E > 200) leading to the corresponding (S)-β-halohydrin with ee > 99 %. However, the time required for an ideal 50 % conversion ranged from 15 min for 2,4-dichlorophenyl chlorohydrin acetate to 216 h for 2-chlorophenyl bromohydrin acetate. Six chlorohydrins and five bromohydrins were evaluated, the latter being less reactive. For the β-brominated substrates, steric hindrance on the aromatic ring played a crucial role, which was not observed for the β-chlorinated derivatives. To shed light on the different reaction rates, docking studies were carried out with all the substrates using MD simulations. The computational data obtained for the β-brominated substrates, based on the parameters analysed such as NAC (near attack conformation), distance between Ser-O and carbonyl-C and oxyanion site stabilization were in agreement with the experimental results. On the other hand, the data obtained for β-chlorinated substrates suggested that physical aspects such as high hydrophobicity or induced change in the conformation of the enzymatic active site are more relevant aspects when compared to steric hindrance effects.
Enantiocomplementary C–H Bond Hydroxylation Combining Photo-Catalysis and Whole-Cell Biocatalysis in a One-Pot Cascade Process
Peng, Yongzhen,Li, Danyang,Fan, Jiajie,Xu, Weihua,Xu, Jian,Yu, Huilei,Lin, Xianfu,Wu, Qi
, p. 821 - 825 (2020/02/20)
Enantiocomplementary hydroxylation of alkyl aromatics through a one-pot photo-biocatalytic cascade reaction is described. The photoredox process is implemented in aqueous phase with O2 as oxidant and the subsequent (R)- or (S)-selective bioreduction is performed by whole cell system without the addition of the expensive cofactor (NADPH). This mild, operationally simple protocol transforms a wide variety of readily available aromatic compounds into valuable chiral alcohols with high yield (up to 90 %) and stereoselectivity (up to 99 %), thereby displaying important potentials in organic synthesis.
