60793-22-8Relevant articles and documents
General chemoenzymatic route to two-stereocenter triketides employing assembly line ketoreductases
Zhang, Zhicheng,Cepeda, Alexis J.,Robles, Mireya L.,Hirsch, Melissa,Kumru, Kaan,Zhou, Jina A.,Keatinge-Clay, Adrian T.
supporting information, p. 157 - 160 (2019/12/25)
Modular polyketide synthases (PKSs) are enzymatic assembly lines that fuse carbon fragments into complex chiral products. Here, their synthetic logic is employed to chemoenzymatically generate two-stereocenter triketides. Each of the four stereoisomers was constructed in a stereocontrolled manner using C-acylation and two PKS ketoreductases possessing opposite stereoselectivities.
Stereodiverse Iterative Synthesis of 1,3-Polyol Arrays through Asymmetric Catalytic Hydrogenation. Formal Total Synthesis of (-)-Cyanolide A
Che, Wen,Li, Yu-Zhen,Liu, Jin-Chi,Zhu, Shou-Fei,Xie, Jian-Hua,Zhou, Qi-Lin
supporting information, p. 2369 - 2373 (2019/03/29)
An iterative protocol was developed for highly diastereo- and enantioselective construction of high-order 1,3-polyols via iridium-catalyzed asymmetric hydrogenation of β-alkyl-β-keto esters. The protocol involves four operations - asymmetric hydrogenation, hydroxy protection, ester hydrolysis, and C-acylation - and the catalyst loading can be as low as 0.005 mol %. The configurations of all stereogenic centers of 1,3-polyols are controlled by the catalyst. By the use of this protocol, a formal total synthesis of the polyketide cyanolide A was achieved with high diastereoselectivity and enantioselectivity.
Copper-Catalyzed Asymmetric Conjugate Additions of Bis(pinacolato)diboron and Dimethylzinc to Acyl- N-methylimidazole Michael Acceptors: A Highly Stereoselective Unified Strategy for 1,3,5,... n (OH, Me) Motif Synthesis
Lauberteaux, Jimmy,Crévisy, Christophe,Baslé, Olivier,De Figueiredo, Renata Marcia,Mauduit, Marc,Campagne, Jean-Marc
supporting information, p. 1872 - 1876 (2019/03/11)
A unified strategy for the construction of prevalent 1,3,5,...n (OH, Me) motifs based on consecutive copper-catalyzed asymmetric conjugate borylation (ACB) and methylation (ACA) reactions involving α,β-unsaturated 2-acyl-N-methylimidazoles is described. Good yields and high diastereoselectivities have been obtained in ACA and ACB reactions for both matched and mismatched pairs as illustrated in the synthesis of syn/anti and anti/anti (Me, OTBS, Me) and (OH, OTBS, Me) motifs.
2-(1S)-Camphanoyloxy-2′-phosphanylbiphenyl Ligands – Synthesis, Structure, and Preliminary Tests in Transition-Metal Catalysis
Wawrzyniak, Piotr,Kindermann, Markus K.,Thede, Gabriele,Thede, Richard,Jones, Peter G.,Enthaler, Stephan,Junge, Kathrin,Beller, Matthias,Heinicke, Joachim W.
, p. 2762 - 2773 (2017/06/06)
Diastereoisomer separation of the (1S)-camphanic acid 2-isopropylphenylphosphanyl-phenyl ester 1 exemplifies the potential of (1S)-camphanoyl chloride for enantiomer separation of hydroxyl-functional asymmetric phosphanes. Esterification of lithium 2′-phosphanylbiphenyl-2-olates, generated from the respective 2-OH or 2-OSiMe3 precursors 2aOH and 2b–fSi, furnished the 2-(1S)-camphanoyloxy-biphenylphosphanes 3a–c as 1:1 mixtures of diastereomers with low barriers for interconversion by rotation around the C–C axis (ΔG# = 70–73 kJ mol–1 for 3a and 3c by 31P VT NMR spectroscopy). The P-asymmetric compounds 3d–f form 1:1 mixtures of stereoisomers. There is a tendency to cocrystallization of two preferred diastereoisomers, as shown by the crystal structure analyses of 3dD and 3fD, and in solution, there is a tendency toward partial isomerization to the sterically less-favored atropisomers. The [RhCl(cod)(3dD)] complex 4dD, however, seems stable in solution. Excess 2dLi reacted with (1S)-camphanoyl chloride preferentially to form the (SP,Rax,1S) isomer, which was separated by crystallization as enantiopure 3dE, characterized by single-crystal XRD. Preliminary screening tests of this ligand in Rh-catalyzed asymmetric hydrogenations of N-(1-phenylvinyl)acetamide allowed high conversion and up to 59 % ee. Hydrosilylation of acetophenone proceeded with 78 % conversion and 48 % ee; Suzuki–Miyaura couplings of 1-bromo-2-naphthol with PhB(OH)2, in the presence of 3b/[Pd(OAc)2], gave yields up to 98 %.
Elucidation of the Stereospecificity of C-Methyltransferases from trans-AT Polyketide Synthases
Xie, Xinqiang,Khosla, Chaitan,Cane, David E.
supporting information, p. 6102 - 6105 (2017/05/08)
S-Adenosyl methionine (SAM)-dependent C-methyltransferases are responsible for the C2-methylation of 3-ketoacyl-acyl carrier protein (ACP) intermediates to give the corresponding 2-methy-3-ketoacyl-ACP products during bacterial polyketide biosynthesis mediated by trans-AT polyketide synthases that lack integrated acyl transferase (AT) domains. A coupled ketoreductase (KR) assay was used to assign the stereochemistry of the C-methyltransferase-catalyzed reaction. Samples of chemoenzymatically generated 3-ketopentanoyl-ACP (9) were incubated with SAM and BonMT2 from module 2 of the bongkrekic acid polyketide synthase. The resulting 2-methyl-3-ketopentanoyl-ACP (10) was incubated separately with five (2R)- or (2S)-methyl specific KR domains. Analysis of the derived 2-methyl-3-hydroxypentanoate methyl esters (8) by chiral GC-MS established that the BonMT2-catalyzed methylation generated exclusively (2R)-2-methyl-3-ketopentanoyl-ACP ((2R)-10). Identical results were also obtained with three additional C-methyltransferases-BaeMT9, DifMT1, and MupMT1-from the bacillaene, difficidin, and mupirocin trans-AT polyketide synthases
Asymmetric hydrogenation by RuCl2(R-Binap)(dmf)n encapsulated in silica-based nanoreactors
Peng, Juan,Wang, Xuefeng,Zhang, Xiaoming,Bai, Shiyang,Zhao, Yaopeng,Li, Can,Yang, Qihua
, p. 666 - 672 (2015/02/19)
The Noyori catalyst RuCl2(R-Binap)(dmf)n has been successfully encapsulated in C-FDU-12 by using the active chlorosilane Ph2Cl2Si as the silylating agent. 31P-NMR results show that there is no strong interaction between the molecular catalyst and the solid support, thus the encapsulated molecular catalyst could move freely in the nanoreactor during the catalytic process. The solid catalyst exhibits high activity and enantioselectivity for the asymmetric hydrogenation of a series of β-keto esters due to the preserved intrinsic properties of RuCl2(R-Binap)(dmf)n encapsulated in the nanoreactor. The solid catalyst could be recycled by simple filtration and be reused at least four times.
Development of Chiral Spiro P-N-S Ligands for Iridium-Catalyzed Asymmetric Hydrogenation of β-Alkyl-β-Ketoesters
Bao, Deng-Hui,Wu, Hui-Ling,Liu, Chao-Lun,Xie, Jian-Hua,Zhou, Qi-Lin
supporting information, p. 8791 - 8794 (2015/11/27)
The chiral tridentate spiro P-N-S ligands (SpiroSAP) were developed, and their iridium complexes were prepared. Introduction of a 1,3-dithiane moiety into the ligand resulted in a highly efficient chiral iridium catalyst for asymmetric hydrogenation of β-alkyl-β-ketoesters, producing chiral β-alkyl-β-hydroxyesters with excellent enantioselectivities (95-99.9 % ee) and turnover numbers of up to 355 000. Bulkyness is the key: New chiral tridentate spiro P-N-S ligands (SpiroSAP) bearing a conformationally constrained 1,3-dithiane moiety were developed. Their iridium catalysts showed excellent enantioselectivities and activity (TON up to 355 000) for asymmetric hydrogenation of β-alkyl-β-ketoesters.
Conjugated microporous polymers with chiral BINAP ligand built-in as efficient catalysts for asymmetric hydrogenation
Wang, Xu,Lu, Sheng-Mei,Li, Jun,Liu, Yan,Li, Can
, p. 2585 - 2589 (2015/05/13)
A series of chiral conjugated microporous polymers (CMPs) based on the chiral (R)-BINAP ligand (BINAP-CMPs) were synthesized with tunable BET surface areas. These solid catalysts show high activities and enantioselectivities for the asymmetric hydrogenation of β-keto esters after coordination with ruthenium species. Moreover, CMPs can realize spatial isolation. Through preventing the formation of dimers and trimers, BINAP-CMPs show much higher activity than BINAP for the Ir-catalyzed asymmetric hydrogenation of quinaldine.
Improved method for immobilization of a chiral complex on PTA/alumina for asymmetric hydrogenation of a β-ketoester
Ahn, Sung-Hyun,Choi, Moo-Seok,Im, Jun-Seop,Sheikh, Rizwan,Park, Yeung-Ho
, p. 55 - 60 (2013/06/26)
Ru-BINAP was immobilized on alumina using the well-known Augustine method with heteropoly acid (HPA) as the anchoring agent ("Augustine catalyst"). The supported catalyst was tested in a high-pressure reaction such as asymmetric hydrogenation of methyl acetoacetate (MAA). Since the activity of the supported catalyst was significantly lower than that of the homogeneous catalyst, the solvent used in preparing PTA/Al2O 3 was changed from ethanol to a solution of HCl. The modified supported catalyst ("modified Augustine catalyst") exhibited higher conversion, better selectivity, and improved enantioselectivity compared with the catalyst prepared by the Augustine method. The modified Augustine catalyst also produced β-hydroxyesters with good yield and enantioselectivity in asymmetric hydrogenation of various β-ketoester derivatives. The modified Augustine catalyst was examined by FT-IR, XRD, NH3-TPD, and ICP-AES, which revealed the existence of strong acid sites formed by HPA with a Keggin structure. These results were attributed to the effect of enhanced acidity on the modified Augustine catalyst.
Continuous-flow asymmetric hydrogenation of the β-keto ester methyl propionylacetate in ionic liquid-supercritical carbon dioxide biphasic systems
Theuerkauf, Jens,Francio, Giancarlo,Leitner, Walter
, p. 209 - 219 (2013/03/14)
A continuous-flow process for the asymmetric hydrogenation of methyl propionylacetate as a prototypical β-keto ester in a biphasic system of ionic liquid and supercritical carbon dioxide (scCO2) is presented. An established ruthenium/2,2′-bis(diphenylphosphino)-1,1′-binaphthyl (BINAP) catalyst was immobilised in an imidazolium-based ionic liquid while scCO2 was used as mobile phase transporting reactants in and products out of the reactor. The use of acidic additives led to significantly higher reaction rates and enhanced catalyst stability albeit at slightly reduced enantioselectivity. High single pass conversions (>90%) and good enantioselectivity (80-82% ee) were achieved in the first 80h. The initial catalyst activity was retained to 91% after 100h and to 69% after 150h time-on-stream, whereas the enantioselectivity remained practically constant during the entire process. A total turnover number of ～21,000 and an averaged space-time yield (STYav) of 149g L-1 h -1 were reached in a long-term experiment. No ruthenium and phosphorus contaminants could be detected via inductively coupled plasma optical emission spectrometry (ICP-OES) in the product stream and almost quantitative retention by the analysis of the stationary phase was confirmed. A comparison between batch-wise and continuous-flow operation on the basis of these data is provided. Copyright
