74006-76-1Relevant academic research and scientific papers
A robust and stereocomplementary panel of ene-reductase variants for gram-scale asymmetric hydrogenation
Nett, Nathalie,Duewel, Sabine,Schmermund, Luca,Benary, Gerrit E.,Ranaghan, Kara,Mulholland, Adrian,Opperman, Diederik J.,Hoebenreich, Sabrina
, (2021/01/25)
We report an engineered panel of ene-reductases (ERs) from Thermus scotoductus SA-01 (TsER) that combines control over facial selectivity in the reduction of electron deficient C[dbnd]C double bonds with thermostability (up to 70 °C), organic solvent tolerance (up to 40 % v/v) and a broad substrate scope (23 compounds, three new to literature). Substrate acceptance and facial selectivity of 3-methylcyclohexenone was rationalized by crystallisation of TsER C25D/I67T and in silico docking. The TsER variant panel shows excellent enantiomeric excess (ee) and yields during bi-phasic preparative scale synthesis, with isolated yield of up to 93 % for 2R,5S-dihydrocarvone (3.6 g). Turnover frequencies (TOF) of approximately 40 000 h?1 were achieved, which are comparable to rates in hetero- and homogeneous metal catalysed hydrogenations. Preliminary batch reactions also demonstrated the reusability of the reaction system by consecutively removing the organic phase (n-pentane) for product removal and replacing with fresh substrate. Four consecutive batches yielded ca. 27 g L?1 R-levodione from a 45 mL aqueous reaction, containing less than 17 mg (10 μM) enzyme and the reaction only stopping because of acidification. The TsER variant panel provides a robust, highly active and stereocomplementary base for further exploitation as a tool in preparative organic synthesis.
Counterion Enhanced Organocatalysis: A Novel Approach for the Asymmetric Transfer Hydrogenation of Enones
Scharinger, Fabian,Márk Pálv?lgyi, ádám,Zeindlhofer, Veronika,Schnürch, Michael,Schr?der, Christian,Bica-Schr?der, Katharina
, p. 3776 - 3782 (2020/06/22)
We present a novel strategy for organocatalytic transfer hydrogenations relying on an ion-paired catalyst of natural l-amino acids as main source of chirality in combination with racemic, atropisomeric phosphoric acids as counteranion. The combination of a chiral cation with a structurally flexible anion resulted in a novel chiral framework for asymmetric transfer hydrogenations with enhanced selectivity through synergistic effects. The optimized catalytic system, in combination with a Hantzsch ester as hydrogen source for biomimetic transfer hydrogenation, enabled high enantioselectivity and excellent yields for a series of α,β-unsaturated cyclohexenones under mild conditions. Moreover, owing to the use of readily available and chiral pool-derived building blocks, it could be prepared in a straightforward and significantly cheaper way compared to the current state of the art.
Asymmetric Synthesis of 2,3-Disubstituted Cyclic Ketones by Enantioselective Conjugate Radical Additions
Nad, Sukanya,Sibi, Mukund P.
, (2019/11/22)
Enantioselective conjugate radical addition to 2-acyloxymethyl cycloalkenones proceeds in high yield with outstanding diastereoselectivity and excellent enantioselectivity using chiral salen Lewis acids. The process provides access to 2,3-disubstituted cycloalkanones, a structural motif present in natural products.
Stereochemical Insights into the Anaerobic Degradation of 4-Isopropylbenzoyl-CoA in the Denitrifying Bacterium Strain pCyN1
Küppers, Julian,Becker, Patrick,Jarling, René,D?rries, Marvin,Caki?, Nevenka,Schmidtmann, Marc,Christoffers, Jens,Rabus, Ralf,Wilkes, Heinz
, p. 4722 - 4731 (2019/03/13)
The constitutions and absolute configurations of two previously unknown intermediates, (1S,2S,4S)-2-hydroxy-4-isopropylcyclohexane-1-carboxylate and (S)-3-isopropylpimelate, of anaerobic degradation of p-cymene in the bacterium Aromatoleum aromaticum pCyN
CuI-Catalysed Enantioselective Alkyl 1,4-Additions to (E)-Nitroalkenes and Cyclic Enones with Phosphino-Oxazoline Ligands
Shin, Minkyeong,Gu, Minji,Lim, Sung Soo,Kim, Min-Jae,Lee, JuHyung,Jin, HyeongGyu,Jang, Yun Hee,Jung, Byunghyuck
, p. 3122 - 3130 (2018/07/06)
Catalytic enantioselective conjugate additions of simple alkyl groups to nitroalkenes or cyclic enones that result in the formation of tertiary C–C bonds are described. For these stereoselective addition reactions, new chiral phosphino-oxazoline ligands w
Catalytic enantioselective conjugate addition of Grignard reagents to cyclic enones using C1-1,1′-bisisoquinoline-based chiral ligands
Qi, Gao,Judeh, Zaher M.A.
experimental part, p. 1585 - 1592 (2012/05/04)
New highly constrained chiral C1-1,1′-bisisoquinoline ligands were examined in the enantioselective conjugate addition of Grignard reagents to cyclohexenone and cyclopentenone. The desired 1,4-adducts were obtained in excellent yield and moderate enantiomeric excess (up to 35%). Copyright Taylor & Francis Group, LLC.
Preparation and characterization of new C2- and C 1-symmetric nitrogen, oxygen, phosphorous, and sulfur derivatives and analogs of TADDOL. part i
Pichota, Arkadius,Gramlich, Volker,Beck, Albert K.,Seebach, Dieter
experimental part, p. 1239 - 1272 (2012/09/21)
The chloro alcohols 4-6 derived from TADDOLs (=α,α, α′,α′-tetraaryl-1,3-dioxolan-4,5-dimethanols) are used to prepare corresponding sulfanyl alcohols, ethers, and amines (Scheme 1 and Table 1). The dithiol analog of TADDOL and derivatives thereof, 45-49,
Synthesis and AChE inhibitory activity of new chiral tetrahydroacridine analogues from terpenic cyclanones
Santos Pisoni, Diego dos,Sobieski da Costa, Jessé,Gamba, Douglas,Petzhold, Cesar Liberato,César de Amorim Borges, Antonio,Ceschi, Marco Antonio,Lunardi, Paula,Saraiva Gon?alves, Carlos Alberto
scheme or table, p. 526 - 535 (2010/04/06)
This work describes the enantioselective synthesis of a new series of terpenic chiral 9-aminotetrahydroacridine analogues. Several chiral ketones were synthesized from natural monoterpenes in an optically active form and subjected to the cyclodehydration reactions with anthranilonitrile in the presence of BF3·Et2O as catalyst. The 9-aminotetrahydroacridine analogues were tested as acetylcholinesterase (AChE) inhibitors. Based on qualitative structure-activity relationship some trends are suggested.
Directed evolution of an enantioselective enoate-reductase: Testing the utility of iterative saturation mutagenesis
Bougioukou, J. Despina,Kille, Sabrina,Taglieber, Andreas,Reetz, Manfredt.
scheme or table, p. 3287 - 3305 (2010/04/30)
Directed evolution utilizing iterative saturation mutagenesis (ISM) has been applied to the old yellow enzyme homologue YqjM in the quest to broaden its substrate scope, while controlling the enantioselectivity in the bioreduction of a set of substituted cyclopentenone and cyclohexenone derivatives. Guided by the known crystal structure of YqjM, 20 residues were selected as sites for saturation mutagenesis, a pooling strategy based on the method of Phizicky [M. R. Martzen, S. M. McCraith, S. L. Spinelli, F. M. Torres, S. Fields, E. J. Grayhack, E. M. Phizicky, Science 1999, 286, 1153-1155] being used in the GC screening process. The genes of some of the hits were subsequently employed as templates for randomization experiments at the other putative hot spots. Both (R)-and (S)-selective variants were evolved using 3-methylcyclohexenone as the model substrate in the asymmetric bioreduction of the olefinic functionality, only small mutant libraries and thus minimal screening effort being necessary. Some of the best mutants also proved to be excellent catalysts when testing other prochiral substrates without resorting to additional mutagenesis/screening experiments. Thus, the results constitute an important step forward in generalizing the utility of ISM as an efficient method in laboratory evolution of enzymes as catalysts in organic chemistry.
Highly enantio- and s-trans C=C bond selective catalytic hydrogenation of cyclic enones: Alternative synthesis of (-)-menthol
Ohshima, Takashi,Tadaoka, Hiroshi,Hori, Kiyoto,Sayo, Noboru,Mashima, Kazushi
scheme or table, p. 2060 - 2066 (2009/04/07)
A highly enantioselective catalytic hydrogenation of cyclic enones was achieved by using the combination of a cationic Rh1 complex, (S)-5,5′-bis{di(3,5-di-tert-butyl-4-methoxyphenylphosphino)}-4, 4′-bi-1,3-benzodioxole (DTBM-SEGPHOS), and (CH2CH 2PPh3Br)2. The presence of an s-cis C=C bond isopropylidene moiety on the cyclic enone influenced the enantioselectivity of the hydrogenation. Thus, the hydrogenation of 3-alkyl-6-isopropylidene-2- cyclohexen-1-one, which contains both s-cis and s-trans enones, proceeded in excellent enantioselectivity (up to 98% ee). To obtain high enantio- and s-trans selectivities, the addition of a halogen source to the cationic Rh complex was the essential step. With the key step of the s-trans selective asymmetric hydrogenation of piperitenone, we demonstrated a new synthetic method for optically pure (-)-menthol via three atom-economical hydrogenations. Moreover, we found that the complete s-trans and s-cis C=C bond selective reactions were also realized by the proper choice of both the chiral ligands and halides.
