86668-34-0Relevant academic research and scientific papers
The Mechanism of Rhodium-Catalyzed Allylic C-H Amination
Harris, Robert J.,Park, Jiyong,Nelson, Taylor A. F.,Iqbal, Nafees,Salgueiro, Daniel C.,Bacsa, John,Macbeth, Cora E.,Baik, Mu-Hyun,Blakey, Simon B.
supporting information, p. 5842 - 5851 (2020/04/10)
Herein, the mechanism of catalytic allylic C-H amination reactions promoted by Cp*Rh complexes is reported. Reaction kinetics experiments, stoichiometric studies, and DFT calculations demonstrate that the allylic C-H activation to generate a Cp*Rh(π-allyl) complex is viable under mild reaction conditions. The role of external oxidants in the catalytic cycle is elucidated. Quantum mechanical calculations, stoichiometric reactions, and cyclic voltammetry experiments concomitantly support an oxidatively induced reductive elimination process of the allyl fragment with an acetate ligand proceeding through a Rh(IV) intermediate. Stoichiometric oxidation and bulk electrolysis of the proposed π-allyl intermediate are also reported to support these analyses. Lastly, evidence supporting the amination of an allylic acetate intermediate is presented. We show that Cp*Rh(III)2+ behaves as a Lewis acid catalyst to complete the allylic amination reaction.
Free and immobilized lecitase ultra as the biocatalyst in the kinetic resolution of (E)‐4‐arylbut‐3‐en‐2‐yl esters
Chojnacka, Anna,Drozd, Rados?aw,G?adkowski, Witold,Le?niarek, Aleksandra,Szymańska, Magdalena
, (2020/03/17)
The influence of buffer type, co‐solvent type, and acyl chain length was investigated for the enantioselective hydrolysis of racemic 4‐arylbut‐3‐en‐2‐yl esters using Lecitase Ultra (LU). Immobilized preparations of the Lecitase Ultra enzyme had
Expanding the Substrate Specificity of Thermoanaerobacter pseudoethanolicus Secondary Alcohol Dehydrogenase by a Dual Site Mutation
Musa, Musa M.,Bsharat, Odey,Karume, Ibrahim,Vieille, Claire,Takahashi, Masateru,Hamdan, Samir M.
, p. 798 - 805 (2018/02/21)
Here, we report the asymmetric reduction of selected phenyl-ring-containing ketones by various single- and dual-site mutants of Thermoanaerobacter pseudoethanolicus secondary alcohol dehydrogenase (TeSADH). The further expansion of the size of the substrate binding pocket in the mutant W110A/I86A not only allowed the accommodation of substrates of the single mutants W110A and I86A within the expanded active site but also expanded the substrate range of the enzyme to ketones bearing two sterically demanding groups (bulky–bulky ketones), which are not substrates for the TeSADH single mutants. We also report the regio- and enantioselective reduction of diketones with W110A/I86A TeSADH and single TeSADH mutants. The double mutant exhibited dual stereopreference to generate the Prelog products most of the time and the anti-Prelog products in a few cases.
Enantioselective NiH/Pmrox-Catalyzed 1,2-Reduction of α,β-Unsaturated Ketones
Chen, Fenglin,Zhang, Yao,Yu, Lei,Zhu, Shaolin
, p. 2022 - 2025 (2017/02/15)
The enantioselective 1,2-reduction of α,β-unsaturated ketones was achieved using a NiH catalyst in the presence of pinacolborane. This mild process represents a general method to access a wide variety of structurally diverse α-chiral allylic alcohols in excellent yields and enantioselectivity, as well as very high levels of ambidoselectivity for 1,2- over 1,4-reduction. Furthermore, for reactions on a 10 mmol scale, catalyst loadings as low as 0.5 mol % could be employed to deliver product without any detrimental effect on the yield, enantio-, or ambidoselectivity.
Characterization of the monolignol oxidoreductase AtBBE-like protein 15 L182V for biocatalytic applications
Pils, Sabine,Schnabl, Kordula,Wallner, Silvia,Daniel, Bastian,Macheroux, Peter,Kljajic, Marko,Kupresanin, Nina,Breinbauer, Rolf,Fuchs, Michael,Rocha, Raquel,Schrittwieser, Joerg H.,Kroutil, Wolfgang
, p. S6 - S14 (2018/04/05)
Monolignol oxidoreductases from the berberine bridge enzyme-like (BBE-like) protein family (pfam 08031) catalyze the oxidation of monolignols to the corresponding aldehydes. In this report, we explore the potential of a monolignol oxidoreductase from Arabidopsis thaliana (AtBBE-like protein 15) as biocatalyst for oxidative reactions. For this study we employed a variant with enhanced reactivity towards oxygen, which was obtained by a single amino acid exchange (L182V). The pH and temperature optima of the purified AtBBE-like protein 15 L182V were determined as well as the tolerance toward organic co-solvents; furthermore the substrate scope was characterized. The enzyme has a temperature optimum of 50 °C and retains more than 50% activity between pH 5 and pH 10 within 5 min. The enzyme shows increased activity in the presence of various co-solvents (10–50% v/v), including acetonitrile, 2-propanol, 1,4-dioxane, and dimethyl sulfoxide. Primary benzylic and primary or secondary allylic alcohols were accepted as substrates. The enantioselectivity E in the oxidation of secondary alcohols was good to excellent (E>34 to?>200).
Hydrogen-bond-promoted palladium catalysis: Allylic alkylation of indoles with unsymmetrical 1,3-disubstituted allyl acetates using chiral bis(sulfoxide) phosphine ligands
Du, Le,Cao, Peng,Xing, Junwei,Lou, Yazhou,Jiang, Liyin,Li, Liangchun,Liao, Jian
supporting information, p. 4207 - 4211 (2013/05/09)
A DYKAT die hard: A new class of chiral BiSO-P ligands were effective for an unprecedented palladium-catalyzed asymmetric allylic alkylation of indoles with the racemic title acetates through a dynamic kinetic asymmetric transformation (DYKAT). The hydrogen bond formed between the sulfinyl group of the ligand and NH of indole plays an important role in the reaction. Copyright
Highly enantioselective synthesis of 3-substituted furanones by palladium-catalyzed kinetic resolution of unsymmetrical allyl acetates
Mao, Bin,Ji, Yining,Fananas-Mastral, Martin,Caroli, Giuseppe,Meetsma, Auke,Feringa, Ben L.
, p. 3168 - 3173 (2012/05/05)
Resolving the issue: A near-perfect Pd-catalyzed kinetic resolution of 1,3-disubstituted unsymmetrical allylic acetates uses silyl enol ethers as nucleophiles to access the important 3-substituted-furanone scaffold (see scheme; DACH=diaminocyclohexyl, dba=dibenzylideneacetone). The reaction proceeds under mild conditions and provides the desired products with excellent chemo-, regio-, and enantioselectivity. Copyright
Enzymatic resolution of chlorohydrins for the synthesis of enantiomerically enriched 2-vinyloxiranes
McCubbin, J. Adam,Maddess, Matthew L.,Lautens, Mark
, p. 289 - 293 (2008/12/21)
A series of vinylchlorohydrins are resolved by enzymatic kinetic resolution. The resulting R-alcohols, obtained in up to 99% ee, are stereoselectively converted into vinyloxiranes in high yield. The S-acetates, obtained in up to 99% ee were either deprotected to S-alcohols, or cyclized directly to vinyl oxiranes under basic conditions, with moderate to no loss in ee. The results are consistent with a racemization mechanism involving reversible migration of the acetate during deprotection. Georg Thieme Verlag Stuttgart.
Asymmetric transesterification of secondary alcohols catalyzed by feruloyl esterase from Humicola insolens
Hatzakis, Nikos S.,Smonou, Ioulia
, p. 325 - 337 (2007/10/03)
A new asymmetric transesterification of secondary alcohols catalyzed by feruloyl esterase from Humicola insolens has been found. Although alcohols are not the natural substrates for this enzyme, a high R enantioselectivity was observed. Stereochemical studies showed that variations in substrate structure lead to strong variations in enantioselectivity. The highest enantioselectivities are obtained when the β-carbon of the secondary alcohol is tertiary or quaternary.
Palladium-catalyzed asymmetric synthesis of allylic alcohols from unsymmetrical and symmetrical racemic allylic carbonates featuring C-O-bond formation and dynamic kinetic resolution
Gais, Hans-Joachim,Bondarev, Oleg,Hetzer, Ralf
, p. 6279 - 6283 (2007/10/03)
Described is the asymmetric synthesis of the allylic alcohols 11 (85% ee), 15 (99% ee), 17 (93% ee), 19 (61% ee), and 21 (69% ee) through a Pd-catalyzed reaction of the unsymmetrical carbonates rac-10, rac-12, rac-14, rac-16, rac-18, and rac-20, respectively, with KHCO3 and H2O in the presence of bisphosphane 6. Similarly the allylic alcohols 23 (99% ee) and 25 (97% ee) have been obtained from the symmetrical carbonates rac-22 and rac-24, respectively. Reaction of the meso-biscarbonate 26 with H2O and Pd(0)/6 afforded alcohol 27 (96% ee), which was converted to the PG building block 32. The unsaturated bisphosphane 33 showed in the synthesis of alcohols 36, 37, and 39 a similar high selectivity as 6. The formation of alcohols 11, 15, and 17 involves an efficient dynamic kinetic resolution.
