22554-27-4Relevant articles and documents
The effect of temperature on the lipase-catalyzed asymmetric protonation of 1-acetoxy-2-methylcyclohexene giving (R)-2-methylcyclohexanone
Sakai, Takashi,Matsuda, Akiko,Tanaka, Yuko,Korenaga, Toshinobu,Ema, Tadashi
, p. 1929 - 1932 (2004)
Lipase-catalyzed enantioface-selective protonation of the enol acetate of 2-methylcyclohexanone was performed by using Burkholderia cepacia lipase immobilized on porous ceramic particles, 'Lipase PS-C II' (Amano Enzyme Inc.), in i-Pr2O and etha
Asymmetric hydrogenation of the C-C double bond of enones with the reductases from Nicotiana tabacum
Hirata, Toshifumi,Shimoda, Kei,Gondai, Takayuki
, p. 850 - 851 (2000)
Three enone reductases, p44, p74, and p90, from the cultured cells of Nicotiana tabacum catalyzed the asymmetric hydrogenation of the C-C double bond of enones. Reduction of 2-alkyl-2-cyclohexen-1-ones with the p44 reductase gave highly optically active (
Metagenomic ene-reductases for the bioreduction of sterically challenging enones
Dobrijevic, Dragana,Benhamou, Laure,Aliev, Abil E.,Méndez-Sánchez, Daniel,Dawson, Natalie,Baud, Damien,Tappertzhofen, Nadine,Moody, Thomas S.,Orengo, Christine A.,Hailes, Helen C.,Ward, John M.
, p. 36608 - 36614 (2019)
Ene-reductases (ERs) of the Old Yellow Enzyme family catalyse asymmetric reduction of activated alkenes providing chiral products. They have become an important method in the synthetic chemists' toolbox offering a sustainable alternative to metal-catalysed asymmetric reduction. Development of new biocatalytic alkene reduction routes, however needs easy access to novel biocatalysts. A sequence-based functional metagenomic approach was used to identify novel ERs from a drain metagenome. From the ten putative ER enzymes initially identified, eight exhibited activities towards widely accepted mono-cyclic substrates with several of the ERs giving high reaction yields and stereoselectivities. Two highly performing enzymes that displayed excellent co-solvent tolerance were used for the stereoselective reduction of sterically challenging bicyclic enones where the reactions proceeded in high yields, which is unprecedented to date with wild-type ERs. On a preparative enzymatic scale, reductions of Hajos-Parish, Wieland-Miescher derivatives and a tricyclic ketone proceeded with good to excellent yields.
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.
Enantioselective Protonation of Enol Esters with Bifunctional Phosphonium/Thiourea Catalysts
Yamamoto, Eiji,Wakafuji, Kodai,Mori, Yusuke,Teshima, Gaku,Hidani, Yuki,Tokunaga, Makoto
, p. 4030 - 4034 (2019/06/07)
Bifunctional phosphonium/thioureas derived from tert-leucine behaved as highly selective catalysts for enantioselective protonation of enol esters, providing α-chiral ketones in yields of up to 99% with high enantioselectivities (up to 98.5:1.5 er). Control experiments clarified that a bulky tert-butyl group and phosphonium and thiourea moieties were necessary to achieve such high stereoselectivity. In addition, mechanistic investigations indicated the catalyst was converted to the corresponding betaine species, which served as a monomolecular catalyst.
