63261-45-0Relevant articles and documents
Microstructure Analysis of Poly(cyclopentene carbonate)s at the Diad Level
Liu, Ye,Li, Rong-Rong,Lu, Xiao-Bing
, p. 6941 - 6947 (2015)
The spectroscopic assignment of poly(cyclopentene carbonate)s at the diad level was performed by using two kinds of model compounds: isotactic and syndiotactic dimers of cyclopentene carbonate unit. By comparing the signals in the carbonyl region, we concluded that the signals at 153.85 and 153.78 ppm in the 13C NMR spectrum of poly(cyclopentene carbonate) were attributed to m-diad and r-diad, respectively. The signals at 82.61 and 82.53 ppm in the 13C NMR spectrum were assigned to m-diad and r-diad peak of methine resonance, respectively. It was found that the carbonate carbon signals were sensitive toward the stereocenters on adjacent epoxide ring-opening units. The syndiotactic and isotactic diads matched well with the microstructures of the stereoregular poly(cyclopentene carbonate)s that were prepared by using chiral dinuclear Co(III) complex catalysts.
One-Pot Enzymatic Synthesis of Cyclic Vicinal Diols from Aliphatic Dialdehydes via Intramolecular C?C Bond Formation and Carbonyl Reduction Using Pyruvate Decarboxylases and Alcohol Dehydrogenases
Zhang, Yan,Yao, Peiyuan,Cui, Yunfeng,Wu, Qiaqing,Zhu, Dunming
, p. 4191 - 4196 (2018/09/25)
An enzymatic cascade reaction was developed for one-pot enantioselective conversion of aliphatic dialdehydes to chiral vicinal diols using pyruvate decarboxylases (PDCs) and alcohol dehydrogenases (ADHs). The PDCs showed promiscuity in catalysing the cyclization of aliphatic dialdehydes through intramolecular stereoselective carbon-carbon bond formation. Consequently, 1,2-cyclopentanediols in three different stereoisomeric forms and 1,2-cyclohexanediols in two different stereoisomeric forms could be prepared with high conversion and stereoisomeric ratio from the respective initial substrates, glutaraldehyde and adipaldehyde. These cascade reactions represent a promising approach to the biocatalytic synthesis of important chiral vicinal diols. (Figure presented.).
Comparing Different Strategies in Directed Evolution of Enzyme Stereoselectivity: Single- versus Double-Code Saturation Mutagenesis
Sun, Zhoutong,Lonsdale, Richard,Li, Guangyue,Reetz, Manfred T.
, p. 1865 - 1872 (2016/11/06)
Saturation mutagenesis at sites lining the binding pockets of enzymes constitutes a viable protein engineering technique for enhancing or inverting stereoselectivity. Statistical analysis shows that oversampling in the screening step (the bottleneck) increases astronomically as the number of residues in the randomization site increases, which is the reason why reduced amino acid alphabets have been employed, in addition to splitting large sites into smaller ones. Limonene epoxide hydrolase (LEH) has previously served as the experimental platform in these methodological efforts, enabling comparisons between single-code saturation mutagenesis (SCSM) and triple-code saturation mutagenesis (TCSM); these employ either only one or three amino acids, respectively, as building blocks. In this study the comparative platform is extended by exploring the efficacy of double-code saturation mutagenesis (DCSM), in which the reduced amino acid alphabet consists of two members, chosen according to the principles of rational design on the basis of structural information. The hydrolytic desymmetrization of cyclohexene oxide is used as the model reaction, with formation of either (R,R)- or (S,S)-cyclohexane-1,2-diol. DCSM proves to be clearly superior to the likewise tested SCSM, affording both R,R- and S,S-selective mutants. These variants are also good catalysts in reactions of further substrates. Docking computations reveal the basis of enantioselectivity.
