14898-79-4Relevant articles and documents
Viditz
, p. 670 (1933)
Dupont,Dulou
, (1935)
Solar Light Induced Formation of Chiral 2-Butanol in an Enzyme-Catalyzed Chemical System
Mandler, Daniel,Willner, Itamar
, p. 5352 - 5353 (1984)
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Hydroboration. 92. Investigation of Practical Methods for the Synthesis of Optically Pure Isopinocampheylchloroborane for the Asymmetric Hydroboration of Representative Prochiral Alkenes
Dhokte, Ulhas P.,Kulkarni, Shekhar V.,Brown, Herbert C.
, p. 5140 - 5148 (1996)
A quantitative study was made of the preparation of the optically pure borane reagent, isopinocampheylchloroborane (IpcBHCl), potentially valuable for asymmetric hydroboration.IpcBHCl (87-90percent) in equilibrium with 5-6.5percent of IpcBCl2 and IpcBH2, respectively, can be prepared conveniently by a number of relatively simple operations: (1) the reaction of isopinocampheylborane (IcpBH2) with anhydrous hydrochloric acid (HCl) in ethyl ether (EE); (2) the reaction of stoichiometric amounts of IpcBH2 with isopinocampheyldichloroborane (IpcBCl2) in EE; and (3) the reduction of IpcBCl2 with trimethylsilane (Me3SiH) or lithium aluminum hydride (LAH) in EE.The reduction of IpcBCl2 with Me3SiH in pentane proceeds extremely slowly to provide the desired reagent, IpcBHCl.However, in EE, the reduction proceeds much faster, providing an equilibrium mixture of 90percent IpcBHCl, 5percent IpcBH2, and 5percent IpcBCl2.We also investigated the reduction of IpcBCl2 with Me3SiH in pentane and dichloromethane (CH2CL2) in the presence of known amounts of EE, tetrahydrofuran (THF), and dimethyl sulfide (SMe2), solvents which coordinate with the dichloroboranes.A comparative study of the rate of hydroboration of the alkene, 2-methyl-2-butene, with IpcBH2 and IpcBHCl, obtained as described above, was made in representative solvents, such as pentane, CH2Cl2, EE, and THF, at 0 deg C and, in many cases, also at 25 deg C.This study revealed that the rate of hydroboration is faster in THF for IpcBH2, while for IpcBHCl, the rate is faster in EE.Asymmetric hydroboration of prochiral alkenes was achieved by two methods, viz., IpcBHCl, produced by the reaction of IpcBH2 with HCl in EE (method A), and the reduction-hydroboration reaction of IpcBCl2 with LAH (0.25 equiv) in the presence of the prochiral alkene (method B) in EE.In both methods, the temperature of the reaction mixture was maintained at -25 deg C.Almost identical results were realized in these two procedures, with the enantiomeric excess (ee) realized with IpcBHCl, in some cases, considerably better than that achieved with IpcBH2.Although, IpcBHCl was obtained in onyl 87090percent purity along with IpcBH2 and IpcBCl2 as side products, the presence of the latter compound had no observable effect on the chiral outcome of the asymmetric hydroboration.
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Leroux,Lucas
, p. 41 (1951)
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Utilization of deep-sea microbial esterase PHE21 to generate chiral sec-butyl acetate through kinetic resolutions
Wang, Yilong,Xu, Yongkai,Zhang, Yun,Sun, Aijun,Hu, Yunfeng
, p. 1027 - 1035 (2018)
We previously identified and characterized 1 novel deep-sea microbial esterase PHE21 and used PHE21 as a green biocatalyst to generate chiral ethyl (S)-3-hydroxybutyrate, 1 key chiral chemical, with high enantiomeric excess and yield through kinetic resolution. Herein, we further explored the potential of esterase PHE21 in the enantioselective preparation of secondary butanol, which was hard to be resolved by lipases/esterases. Despite the fact that chiral secondary butanols and their ester derivatives were hard to prepare, esterase PHE21 was used as a green biocatalyst in the generation of (S)-sec-butyl acetate through hydrolytic reactions and the enantiomeric excess, and the conversion of (S)-sec-butyl acetate reached 98% and 52%, respectively, after process optimization. Esterase PHE21 was also used to generate (R)-sec-butyl acetate through asymmetric transesterification reactions, and the enantiomeric excess and conversion of (R)-sec-butyl acetate reached 64% and 43%, respectively, after process optimization. Deep-sea microbial esterase PHE21 was characterized to be a useful biocatalyst in the kinetic resolution of secondary butanol and other valuable chiral secondary alcohols.
Hydroboration. 83. Synthesis and Hydroboration of 2-Ethylapopinene. Comparison of Monoisopinocampheylborane and Its 2-Ethyl Analogue for the Chiral Hydroboration of Representative Alkenes
Brown, Herbert C.,Randad, Ramnarayan S.,Bhat, Krishna S.,Zaidlewicz, Marek,Weissman, Steven A.,et al.
, p. 5513 - 5518 (1988)
Reduction of nopol tosylate gives the new chiral ligand (-)-2-ethylapopinene (90.2percent ee) with higher steric requirements than those of α-pinene.Reaction of borane with (-)-2-ethylapopinene in THF at 0 deg C, in a molar ratio of 1:2, provides an equilibrium mixture of mono- and dialkylboranes EapBH2 and Eap2BH.With an excess of (-)-2-ethylapopinene (1:10; BMS/2-ethylapopinene), the formation of bis(2-ethylapoisopinocampheyl)borane, Eap2BH, is essentially quantitative (ca. 98percent).Treatment of the equilibrium mixture of boranes (Eap2BH, EapBH2) with TMED at 34 deg C precipitates crystalline (EapBH2)2*TMED.Treatment of the crystalline product with BF3*OEt2 gives EapBH2 (mono(2-ethylapoisopinocampheyl)borane) of essentially 100percent ee, enantiomerically purer than the (-)-2-ethylapopinene (ca. 90percent ee) utilized for the preparation.Hydroboration of a series of olefins with EapBH2, followed by oxidation of the intermediate organoborane, produces the corresponding alcohols with significantly improved enantiomeric purities over those realized with IpcBH2 under the same conditions.Liberation of the olefin from purified EapBH2 provides (-)-2-ethylapopinene (D23 -46.2 deg (neat) in high optical purity (>99percent ee).Metalation of (+)-α-pinene (D23 +51.4 deg (neat)) with the Lochmann reagent, followed by alkylation with methyl iodide, provides in high optical purity (>99percent ee) (+)-2-ethylapopinene (D23 +46.4 deg (neat)), unavailable from commercial (-)-nopol.
Asymmetric transfer hydrogenation of alkyl/aryl or alkyl/methyl ketones catalyzed by known C2-symmetric ferrocenyl-based chiral bis(phosphinite)-Ru(II), Rh(I) and Ir(III) complexes
Durap, Feyyaz,Karaka?, Duygu Elma,Ak, Bünyamin,Baysal, Akin,Aydemir, Murat
, p. 92 - 97 (2016)
Known Ru(II), Rh(I) and Ir(III) complexes of C2-symmetric ferrocenyl based chiral bis(phoshinite) ligands were catalyzed the asymmetric transfer hydrogenation of alkyl/aryl or alkyl methyl ketones. Corresponding secondary alcohols were obtained with high enantioselectivities up to 98% ee and reactivities using iso-propanol as the hydrogen source.
Preparation and characterization of the chirally modified rapidly quenched skeletal Ni catalyst for enantioselective hydrogenation of butanone to R-(-)-2-butanol
Lou, Zhiying,Chen, Xueying,Tian, Li,Qiao, Minghua,Fan, Kangnian,He, Heyong,Zhang, Xiaoxin,Zong, Baoning
, p. 113 - 120 (2010)
A rapidly quenched skeletal Ni (RQ Ni) prepared by the melt-spinning method followed by alkali leaching was used as a new category of Ni precursor to fabricate effective chiral Ni catalyst. A series of tartaric acid (TA)-NaBr-modified RQ Ni catalysts (MRQNi) were derived, and the textural and structural properties of the MRQNi catalysts were systematically investigated. It is found that the modification conditions influence profoundly the composition, texture, and Ni crystallite size of the MRQNi catalysts. In liquid phase hydrogenation of butanone to R-(-)-2-butanol, the optimized MRQNi catalyst exhibits much better activity and enantioselectivity than the similarly chirally modified Raney Ni catalyst. Based on the characterizations, the superior catalytic performance of the MRQNi catalyst is mainly attributed to the higher surface content of the sodium-nickel(II) tartrate complex than that on the chirally modified Raney Ni catalyst.
Novel highly efficient absolute optical resolution method by serial combination of two asymmetric reactions from acetylene monomers having racemic substituents
Aoki, Toshiki,Kaneko, Takashi,Liu, Lijia,Suzuki, Junpei,Tang, Yanan,Teraguchi, Masahiro
supporting information, p. 450 - 461 (2022/01/15)
For general optical resolution, an optical resolution agent is necessary, and the best agent should be selected for each racemic compound. In this study, we will report that a novel optical resolution method by circularly polarized light (CPL) without any
Half-sandwich rhodium complex with ortho-position carborane benzoxazole structure as well as preparation method and application of half-sandwich rhodium complex
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Paragraph 0051-0056, (2021/03/24)
The invention relates to a half-sandwich rhodium complex with an ortho-position carborane benzoxazole structure as well as a preparation method and application of the half-sandwich rhodium complex. The structural formula of the rhodium complex is shown in the specification. The preparation method comprises the following steps: firstly, adding an n-BuLi solution into an ortho-position carborane solution, and then reacting for 30-60 minutes at room temperature; adding bromo-benzoxazole, and carrying out a reaction for 6-8 h at a room temperature; and adding [Cp * RhCl2] 2, reacting at room temperature for 3-5 hours, and carrying out post-treatment to obtain the rhodium complex. The rhodium complex can be used as a catalyst to catalyze the asymmetric reduction reaction of aliphatic chiral alcohol compounds synthesized from aliphatic ketones. Compared with the prior art, the rhodium complex disclosed by the invention has the advantages of simple preparation method, stable physicochemical properties, high catalytic activity for asymmetric reduction reaction of aliphatic ketone, mild reaction conditions and the like.
Synthesis of cis-1,2-diol-type chiral ligands and their dioxaborinane derivatives: Application for the asymmetric transfer hydrogenation of various ketones and biological evaluation
Kilic, Ahmet,Balci, Tu?ba Ersayan,Arslan, Nevin,Aydemir, Murat,Durap, Feyyaz,Okumu?, Veysi,Tekin, Recep
, (2020/06/10)
Two cis-1,2-diol-type chiral ligands (T1 and T2) and their tri-coordinated chiral dioxaborinane (T(1–2)B(1–2)) and four-coordinated chiral dioxaborinane adducts with 4-tert-butyl pyridine sustained by N → B dati
