98919-68-7Relevant 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.
Chemoselective Oxidation of p-Methoxybenzyl Ethers by an Electronically Tuned Nitroxyl Radical Catalyst
Hamada, Shohei,Sugimoto, Koichi,Elboray, Elghareeb E.,Kawabata, Takeo,Furuta, Takumi
supporting information, p. 5486 - 5490 (2020/07/24)
The oxidation of p-methoxy benzyl (PMB) ethers was achieved using nitroxyl radical catalyst 1, which contains electron-withdrawing ester groups adjacent to the nitroxyl group. The oxidative deprotection of the PMB moieties on the hydroxy groups was observed upon treatment of 1 with 1 equiv of the co-oxidant phenyl iodonium bis(trifluoroacetate) (PIFA). The corresponding carbonyl compounds were obtained by treating the PMB-protected alcohols with 1 and an excess of PIFA.
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.
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.
Acylative Kinetic Resolution of Alcohols Using a Recyclable Polymer-Supported Isothiourea Catalyst in Batch and Flow
Neyyappadath, Rifahath Mon,Chisholm, Ross,Greenhalgh, Mark D.,Rodríguez-Escrich, Carles,Pericàs, Miquel A.,H?hner, Georg,Smith, Andrew D.
, p. 1067 - 1075 (2018/02/14)
A polystyrene-supported isothiourea catalyst, based on the homogeneous catalyst HyperBTM, has been prepared and used for the acylative kinetic resolution of secondary alcohols. A wide range of alcohols, including benzylic, allylic, and propargylic alcohols, cycloalkanol derivatives, and a 1,2-diol, has been resolved using either propionic or isobutyric anhydride with good to excellent selectivity factors obtained (28 examples, s values up to 600). The catalyst can be recovered and reused by a simple filtration and washing sequence, with no special precautions needed. The recyclability of the catalyst was demonstrated (15 cycles) with no significant loss in either activity or selectivity. The recyclable catalyst was also used for the sequential resolution of 10 different alcohols using different anhydrides with no cross-contamination between cycles. Finally, successful application in a continuous flow process demonstrated the first example of an immobilized Lewis base catalyst used for the kinetic resolution of alcohols in flow.
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.
Enantioselective Hydroazidation of Trisubstituted Non-Activated Alkenes
Meyer, Daniel,Renaud, Philippe
, p. 10858 - 10861 (2017/08/30)
A one-pot procedure for the enantioselective hydroazidation of non-activated trisubstituted alkenes is described. Hydroboration with monoisopinocampheylborane (IpcBH2) provides dialkylboranes that are in situ selectively converted into monoalkyl-substituted catecholboranes; these undergo radical azidation upon treatment with benzenesulfonyl azide and a radical initiator. Enantiomerically enriched azides were thus obtained in yields of 59–81 % and enantioselectivities of up to 94:6 e.r. (98:2 e.r. if the intermediate dialkylborane is purified by crystallization). A rapid access to enantiomerically pure (+)-rodocaine is also described. The use of other arenesulfonyl radical traps enables enantioselective hydroallylation, hydrosulfanylation, and hydrobromination reactions with yields of 71–86 %.
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.
