252888-53-2Relevant academic research and scientific papers
“Top” or “bottom” switches of a cyclohexanone monooxygenase controlling the enantioselectivity of the sandwiched substrate
Hu, Yujing,Wang, Jie,Cen, Yixin,Zheng, He,Huang, Meilan,Lin, Xianfu,Wu, Qi
, p. 2198 - 2201 (2019)
Single mutation at the switch residues F432 (F432I/L) or L435 (L435A/G) efficiently reversed the inherent enantiopreference of WT CHMOAcineto in the Baeyer-Villiger oxidation of various 4-phenyl-cyclohexanone derivatives and 4-alkyl-cyclohexanones, producing a series of substituted lactones with inversed configuration (up to 99% ee and 99% conversion).
The mutagenesis of a single site for enhancing or reversing the enantio- or regiopreference of cyclohexanone monooxygenases
Hu, Yujing,Xu, Weihua,Hui, Chenggong,Xu, Jian,Huang, Meilan,Lin, Xianfu,Wu, Qi
supporting information, p. 9356 - 9359 (2020/11/02)
The mutagenesis of a "second sphere"switch residue of CHMOAcineto could control its enantio- and regiopreference. Replacing phenylalanine (F) at position 277 of CHMOAcineto into larger tryptophan (W) enabled a significant enhancement of enantio- or regioselectivity toward structurally diverse substrates, moreover, a complete reversal of enantio- or regiopreference was realized by mutating F277 into a range of smaller amino acids (A/C/D/E/G/H/I/K/L/M/N/P/Q/R/S/T/V).
Catalytic asymmetric Baeyer-Villiger oxidation in water by using Pt IIcatalysts and hydrogen peroxide: Supramolecular control of enantioselectivity
Cavarzan, Alessandra,Bianchini, Giulio,Sgarbossa, Paolo,Lefort, Laurent,Gladiali, Serafino,Scarso, Alessandro,Strukul, Giorgio
experimental part, p. 7930 - 7939 (2010/03/31)
The enantioselective BaeyerVilliger oxidation of cyclic ketones is a challenging reaction, especially when using environmentally friendly oxidants. The reaction was carried out in water by using soft Lewis acid PtII complexes that have chiral diphosphines as well as monophosphines. Addition of a surfactant is crucial, which leads to the formation of micelles that act as nanoreactors in which the substrate and catalyst encounter each other in an ordered medium that in several cases positively influences both the conversion and the selectivity of the reactions. This is due to the combination of the hydrophobic effect (which confines the components of the reaction in the micelles), together with supramolecular interactions between the partners within the ordered palisade provided by the alkyl chains of the surfactant. For the oxidation of wieso-cyclobutanones, addition of surfactant allowed the reaction to proceed in high yields and the enantiometic excess (ee; 56%) was higher than in organic solvents. Subsequent extension to meso-cyclohexanones resulted in a general decrease in yields but an enhancement of enantioselectivity (ee up to 92%) moving from organic to water-surfactant media, regardless of the substrate or the catalyst employed. Different behaviour was observed with chiral cyclobutanones 7 and 10: with 7 the best catalyst was 1g, whereas with the larger substrate, 10, complexes 1a-b performed better in terms of enantioselectivity. Each combination of substrate, catalyst and surfactant is a new system and supramolecular reciprocal interactions together with the hydrophobic character of the counterparts play crucial roles. The asymmetric Baeyer-Villiger oxidation in water catalyzed by 1a-h in the presence of micelles is a viable reaction that often benefits from the hydrophobic effect, leading to substantial increases in enantioselectivity.
