34281-92-0Relevant academic research and scientific papers
Synthesis method of chiral trans-2-substituted naphthenic alcohol
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Paragraph 0041-0045; 0050-0051; 0060-0061, (2021/09/08)
The invention relates to a synthesis method of chiral trans-2-substituted naphthenic alcohol. The invention provides a method for synthesizing chiral trans-cycloalkanol through asymmetric hydrogenation of palladium-catalyzed 2-substituted cyclic ketone. According to the method,a chiral diphosphine P-P * complex of metal palladium is taken as a catalyst, an acid additive is used in cooperation, asymmetric hydrogenation is carried out on a 2-substituted cyclic ketone compound to obtain a corresponding chiral trans-cycloalkanol compound. the enantiomeric excess of the chiral trans-cycloalkanol compound can reach 97% at most, and the trans-selectivity of the chiral trans-cycloalkanol compound is up to 20: 1. The method is simple and convenient to operate, practical, easy to implement, high in yield, high in atom economy and environment-friendly; the catalyst is commercially available; the reaction conditions are mild; and the method has a potential practical application value.
Aqueous chemoenzymatic one-pot enantioselective synthesis of tertiary α-aryl cycloketonesviaPd-catalyzed C-C formation and enzymatic C=C asymmetric hydrogenation
Luan, Pengqian,Liu, Yunting,Li, Yongxing,Chen, Ran,Huang, Chen,Gao, Jing,Hollmann, Frank,Jiang, Yanjun
, p. 1960 - 1964 (2021/03/26)
An aqueous chemoenzymatic cascade reaction combining Pd-catalyzed C-C formation and enzymatic C=C asymmetric hydrogenation (AH) was developed for enantioselective synthesis of tertiary α-aryl cycloketones in good yields and excellent enantioselectivities. The stereopreference of the enzyme in AH of α-aryl cyclohexenones was studied. An enantiocomplementary enzyme was obtained by site-directed mutation.
Palladium-catalyzed asymmetric hydrogenation of 2-aryl cyclic ketones for the synthesis oftranscycloalkanols through dynamic kinetic resolution under acidic conditions
Li, Xiang,Zhao, Zi-Biao,Chen, Mu-Wang,Wu, Bo,Wang, Han,Yu, Chang-Bin,Zhou, Yong-Gui
supporting information, p. 5815 - 5818 (2020/06/03)
The first efficient palladium-catalyzed asymmetric hydrogenation of 2-aryl cyclic ketones has been described through dynamic kinetic resolution under acidic conditions, providing a facile access to chiraltranscycloalkanol derivatives with excellent enantioselectivities.
Preparation method of (1S, 2R)-2-phenylcyclohexanol
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Paragraph 0011-0013; 0015-0018, (2020/06/02)
The invention provides a preparation method of (1S, 2R)-2-phenylcyclohexanol. The preparation method specifically comprises the following steps: mixing and reacting a cyclohexene oxide solution, a tetrahydrofuran solution of phenyl magnesium bromide, and cuprous chloride or cuprous bromide for 1-3 h, and performing quenching treatment with an aqueous saturated ammonium chloride or saturated ammonium sulfate solution; and collecting the obtained upper organic layer, carrying out concentration, distillation and recrystallization treatment to obtain a raceme of chiral 2-phenylcyclohexanol, and carrying out resolution treatment on the raceme of chiral 2-phenylcyclohexanol to obtain (1S, 2R)-2-phenylcyclohexanol. The method allows the ee value of the obtained product to reach 98% or above, theprocess is simple, and the product purity is high.
A Practical and Stereoselective In Situ NHC-Cobalt Catalytic System for Hydrogenation of Ketones and Aldehydes
Zhong, Rui,Wei, Zeyuan,Zhang, Wei,Liu, Shun,Liu, Qiang
supporting information, p. 1552 - 1566 (2019/06/14)
Homogeneous catalytic hydrogenation of carbonyl groups is a synthetically useful and widely applied organic transformation. Sustainable chemistry goals require replacing conventional noble transition metal catalysts for hydrogenation by earth-abundant base metals. Herein, we report how a practical in situ catalytic system generated by easily available pincer NHC precursors, CoCl2, and a base enabled efficient and high-yielding hydrogenation of a broad range of ketones and aldehydes (over 50 examples and a maximum turnover number [TON] of 2,610). This is the first example of NHC-Co-catalyzed hydrogenation of C=O bonds using flexible pincer NHC ligands consisting of a N-H substructure. Diastereodivergent hydrogenation of substituted cyclohexanone derivatives was also realized by fine-tuning of the steric bulk of pincer NHC ligands. Additionally, a bis(NHCs)-Co complex was successfully isolated and fully characterized, and it exhibits excellent catalytic activity that equals that of the in-situ-formed catalytic system. Catalytic hydrogenation is a powerful tool for the reduction of organic compounds in both fine and bulk chemical industries. To improve sustainability, more ecofriendly, inexpensive, and earth-abundant base metals should be employed to replace the precious metals that currently dominate the development of hydrogenation catalysts. However, the majority of the base-metal catalysts that have been reported involve expensive, complex, and often air- and moisture-sensitive phosphine ligands, impeding their widespread application. From a mixture of the stable CoCl2, imidazole salts, and a base, our newly developed catalytic system that formed easily in situ enables efficient and stereoselective hydrogenation of C=O bonds. We anticipate that this easily accessible catalytic system will create opportunities for the design of practical base-metal hydrogenation catalysts. A practical in situ catalytic system generated by a mixture of easily available pincer NHC precursors, CoCl2, and a base enabled highly efficient hydrogenation of a broad range of ketones and aldehydes (over 50 examples and up to a turnover number [TON] of 2,610). Diastereodivergent hydrogenation of substituted cyclohexanone derivatives was also realized in high selectivities. Moreover, the preparation of a well-defined bis(NHCs)-Co complex via this pincer NHC ligand consisting of a N-H substructure was successful, and it exhibits equally excellent catalytic activity for the hydrogenation of C=O bonds.
Synthesis of Chiral Cyclic Alcohols from Chiral Epoxides by H or N Substitution with Frontside Displacement
Da Silva Gomes, Roberto,Reddy, Karla Mahender,Corey
, p. 6310 - 6313 (2018/10/09)
Diverse examples are provided of enantioselective sequences for the transformation of cycloalkenes to either chiral trans-β-substituted cycloalkanols or chiral α-amino ketones.
(Poly)cationic λ3-Iodane-Mediated Oxidative Ring Expansion of Secondary Alcohols
Walters, Jennifer C.,Tierno, Anthony F.,Dubin, Aimee H.,Wengryniuk, Sarah E.
supporting information, p. 1460 - 1464 (2018/04/06)
Herein, a simplified approach to the synthesis of medium-ring ethers through the electrophilic activation of secondary alcohols with (poly)cationic λ3-iodanes (N-HVIs) is reported. Excellent levels of selectivity are achieved for C–O bond migration over established α-elimination pathways, enabled by the unique reactivity of a novel 2-OMe-pyridine-ligated N-HVI. The resulting hexafluoroisopropanol (HFIP) acetals are readily derivatized with a range of nucleophiles, providing a versatile functional handle for subsequent manipulations. The utility of this methodology for late-stage natural product derivatization was also demonstrated, providing a new tool for diversity-oriented synthesis and complexity-to-diversity (CTD) efforts. Preliminary mechanistic investigations reveal a strong effect of alcohol conformation on the reactive pathway, thus providing a predictive power in the application of this approach to complex molecule synthesis.
Diastereoselective and enantioselective alkaline-hydrolysis of 2-aryl-1-cyclohexyl acetate: a CAL-B catalyzed deacylation/acylation tandem process
Belkacemi, Fatma Zahra,Merabet-Khelassi, Mounia,Aribi-Zouioueche, Louisa,Riant, Olivier
supporting information, p. 1644 - 1650 (2017/10/12)
Candida antarctica lipase proved to be a particularly efficient lipase for the resolution of racemic 2-arylcyclohexyl acetate in hydrolysis reaction with Na2CO3 in an organic medium. The (1R,2S)-trans-2-arylcyclohexanols 2a–2d were obtained with high ee values (up to >99%) and the selectivity reached E > 200. The influence of the enol ester and the solvent on (±)-trans-2-arylcyclohexanol in the CAL-B catalyzed acylation was also studied and compared with the deacylation. The CAL-B exhibits a better affinity for the alkaline hydrolysis reaction compared with acylation with the enol esters in the same organic solvents. The best conditions were applied to resolve a stereoisomeric mixture cis/trans-2-phenyl-1-cyclohexanol and its corresponding acetate by acylation and deacylation. The obtained results show a highly enantio- and diastereoselectivity of the CAL-B during the acylation and the deacylation in favor of the trans-(R)-enantiomer product. The resolution of a mixture of cis/trans-2-arylcyclohexanols was an easy, convenient approach to provide only one stereoisomer of a mixture of four with high enantiomeric excess.
Directed β C-H Amination of Alcohols via Radical Relay Chaperones
Wappes, Ethan A.,Nakafuku, Kohki M.,Nagib, David A.
, p. 10204 - 10207 (2017/08/10)
A radical-mediated strategy for β C-H amination of alcohols has been developed. This approach employs a radical relay chaperone, which serves as a traceless director that facilitates selective C-H functionalization via 1,5-hydrogen atom transfer (HAT) and enables net incorporation of ammonia at the β carbon of alcohols. The chaperones presented herein enable direct access to imidate radicals, allowing their first use for H atom abstraction. A streamlined protocol enables rapid conversion of alcohols to their β-amino analogs (via in situ conversion of alcohols to imidates, directed C-H amination, and hydrolysis to NH2). Mechanistic experiments indicate HAT is rate-limiting, whereas intramolecular amination is product- and stereo-determining.
Synthetically useful variants of industrial lipases from: Burkholderia cepacia and Pseudomonas fluorescens
Yoshida, Kazunori,Ono, Masakazu,Yamamoto, Takahiro,Utsumi, Takashi,Koikeda, Satoshi,Ema, Tadashi
supporting information, p. 8713 - 8719 (2017/11/03)
Industrial enzymes lipase PS (LPS) and lipase AK (LAK), which originate from Burkholderia cepacia and Pseudomonas fluorescens, respectively, are synthetically useful biocatalysts. To strengthen their catalytic performances, we introduced two mutations into hot spots of the active sites (residues 287 and 290). The LPS-L287F/I290A double mutant showed high catalytic activity and enantioselectivity for poor substrates for which the wild-type enzyme showed very low activity. The LAK-V287F/I290A double mutant was also an excellent biocatalyst with expanded substrate scope, which was comparable to the LPS-L287F/I290A double mutant. Thermodynamic parameters were determined to address the origin of the high enantioselectivity of the double mutant. The ΔΔH? term, but not the ΔΔS? term, was predominant, which suggests that the enantioselectivity is driven by a differential energy associated with intermolecular interactions around Phe287 and Ala290. A remarkable solvent effect was observed, giving a bell-shaped profile between the E values and the log&P or ? values of solvents with the highest E value in i-Pr2O. This suggests that an organic solvent with appropriate hydrophobicity and polarity provides the double mutant with some flexibility that is essential for excellent catalytic performance.
