1. Enantioselective resolution of (±)-1-phenylethanol and (±)-1-phenylethyl acetate by a novel esterase from bacillus sp. Scsio 15121.
Yunfeng Hu, Aijun Sun, Jiayuan Liang, Dun Deng, Yun Zhang. Appl Biochem Biotechnol. 2016 Feb; 178(3): 558-75. DOI: 10.1007/s12010-015-1894-6. PMID: 26467742.
A novel microbial esterase BSE01281 identified from the Indian Ocean was cloned, expressed, and functionally characterized. Esterase BSE01281 could enanoselectively resolve (±)-1-phenylethanol and (±)-1-phenylethyl acetate through two types of enzymatic reactions. After the optimization of enzymatic reactions, BSE01281 could efficiently generate (R)-1-phenylethyl acetate with high enantiomeric excess (>99%) and high conversion (42%) after 96 h trans-esterification reactions. Additionally, BSE01281 could also produce (R)-1-phenylethanol (e.e. > 99%) and (S)-1-phenylethyl acetate (e.e. > 95%) at a conversion of 49% through direct hydrolysis of inexpensive racemic 1-phenylethyl acetate for 8 h. Optically pure (R)-1-phenylethanol generated from direct enzymatic hydrolysis of racemic 1-phenylethyl acetate by BSE01281 is not easily prepared by dehydrogenases, which generally follow the "Prelog's rule" and give (S)-1-phenylethanol instead.
2. Efficient kinetic resolution of (rs)-1-phenylethanol by a mycelium-bound lipase from a wild-type aspergillus oryzae strain.
Hong-De Yan, Zhao Wang, Jun-Qing Qian. Biotechnol Appl Biochem. 2017 Mar; 64(2): 251-258. DOI: 10.1002/bab.1484. PMID: 26854002.
A mycelium-bound lipase from Aspergillus oryzae (AOL) exhibited excellent enantioselectivity for kinetic resolution of (RS)-1-phenylethanol ((RS)-1-PE) in organic solvent. The various reaction parameters affecting the conversion and enantioselectivity were studied, including type of acyl donor, solvent, molar ratio, temperature, enzyme amount, and substrate concentration. The optimum reaction conditions were found to be transesterification with vinyl acetate at 30 °C in methyl tert-butyl ether with a vinyl acetate: (RS)-1-PE molar ratio of 1:1 and an enzyme concentration of 60 g/L. At the optimum reaction conditions, the conversion could reach above 46% with >99% enantiomeric excess of the product, (R)-1-phenylethyl acetate, when the substrate concentration was below 1.4 M. The enzyme displayed an excellent enantioselectivity with an E-value of >200 and a strong tolerance for high substrate concentration of up to 1.8 M. Those results indicated that AOL was a promising biocatalyst in the kinetic resolution of (RS)-1-PE.
3. High-resolution absorption and electronic circular dichroism spectra of (r)-(+)-1-phenylethanol. Confident interpretation based on the synergy between experiments and computations.
Ulrich Boesl, Jörn Lepelmeier, Fabrizio Santoro, Farinaz Mortaheb, Aras Kartouzian, Ulrich Heiz. Chemphyschem. 2018 Mar 19; 19(6): 715-723. DOI: 10.1002/cphc.201701254. PMID: 29239510.
Using density functional theory and its time-dependent extension for excited states, the S0→S1high-resolution vibronic absorption and electronic circular dichroism spectra of (R)-(+)-1-phenylethanol are computed and compared to experimental spectra measured in jet-cooled conditions in the region within 1000 cm-1of the 0-0 transition. The agreement between theory and computation is satisfactory and allows a confident assignment of several experimental bands in terms of fundamentals of different modes. Cases are documented for which the analysis of optical anisotropy factors, owing to their signed nature, remarkably enhances the possibility of a robust assignment of the experimental absorption bands. Computational analysis shows that the experimental spectra are dominated by Herzberg-Teller contributions and that the electronic circular dichroism spectrum and the anisotropy factors are also strongly modulated by the effect of Duschinsky mixings.
