82679-55-8Relevant articles and documents
Catalytic Mechanism Study on the 1,2- and 1,4-Transfer Hydrogenation of Ketimines and β-Enamino Esters Catalyzed by Axially Chiral Biscarboline-Based Alcohols
Dong, Mengxian,Wang, Jie,Wu, Shijie,Zhao, Yang,Ma, Yangyang,Xing, Yongfei,Cao, Fei,Li, Longfei,Li, Zhenqiu,Zhu, Huajie
supporting information, p. 4602 - 4610 (2019/08/30)
Axial N-O alcohols, which have two large carboline moieties connected to the axis were synthesized and used in catalytic enantioselective 1,2- and 1,4-transfer hydrogenations of total 26 ketimines and β-enamino esters. Excellent levels of enantioselectivity ranging from 91% to 99% were achieved by using catalyst (aS)-(S)-3,3′-bis((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9′-dimethyl-9H,9′H-[1,1′-bipyrido[3,4-b]indole] 2-oxide. Interestingly, a mixture of (aS)-(S)-3,3′-bis((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9′-dimethyl-9H,9′H-[1,1′-bipyrido[3,4-b]indole] 2-oxide and (aR)-(S)-3,3′-bis((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9′-dimethyl-9H,9′H-[1,1′-bipyrido[3,4-b]indole] 2-oxide was also able to provide high enantioselectivities up to 95% that is the same as that using pure (aS)-(S)-3,3′-bis((S)-2-(hydroxymethyl)pyrrolidine-1-carbonyl)-9,9′-dimethyl-9H,9′H-[1,1′-bipyrido[3,4-b]indole] 2-oxide. A plausible catalytic mechanism was suggested and total four kinds of transition states (TS) including almost 60 TS structures were investigated using density functional theory (DFT) with different basis sets such as 6-311G(2d,p). The predicted activation energy data are consistent with the experimental results. (Figure presented.).
HR-MALDI-MS imaging assisted screening of β-Carboline alkaloids discovered from mycena metata
Jaeger, Robert J. R.,Lamshoeft, Marc,Gottfried, Sebastian,Spiteller, Michael,Spiteller, Peter
, p. 127 - 134 (2013/06/27)
Fruiting bodies of Mycena metata were screened for the presence of new secondary metabolites by means of HPLC-UV, LC-HR-ESIMS, and high-resolution matrix-assisted laser desorption/ionization mass spectrometry imaging (HRMALDI- MS imaging). Thus, a new β-carboline alkaloid, 6-hydroxymetatacarboline D (1d), was isolated from fruiting bodies of M. metata. 6-Hydroxymetatacarboline D consists of a highly substituted β-carboline skeleton, which is likely to be derived biosynthetically from L-tryptophan, 2-oxoglutaric acid, L-threonine, and L-proline. The structure of the alkaloid was established by 2D NMR spectroscopic methods and HR-ESIMS. Moreover, by extensive application of LC-HR-ESIMS, LC-HR-ESIMS/MS, and LC-HR-ESIMS3 techniques we were able to elucidate the structures of a number of accompanying β-carboline alkaloids, 1a- 1c, 1e-1i, and 2a-2g, structurally closely related to 6-hydroxymetatacarboline D, which are present in M. metata in minor amounts. The absolute configuration of the stereogenic centers of the β-carboline alkaloids was determined by GC-MS comparison with authentic synthetic samples after hydrolytic cleavage and derivatization of the resulting amino acids.
Following the lipase catalyzed enantioselective hydrolysis of amino acid esters with capillary electrophoresis using contactless conductivity detection
Schuchert-Shi, Aiping,Hauser, Peter C.
experimental part, p. 331 - 335 (2010/11/16)
The progress of the enzymatic hydrolysis of racemic mixtures of the enantiomers of the methyl esters of serine and threonine was monitored. This was possible in a reaction vessel of 1.5 mL by direct sampling of volumes in the nanoliter-range directly into an electrophoresis capillary. Contactless conductivity detection was used for quantification as the analytes are not accessible by UV-detection in capillary electrophoresis. Porcine pancreatic lipase and wheat germ lipase both showed a preference for the L-enantiomers of both amino acid esters. The selectivity of the porcine lipase between the two L-esters of the two amino acids was also studied and it was found that the production of L-threonine had priority over L-serine.
