55869-99-3Relevant articles and documents
Evidence for Modulation of Oxygen Rebound Rate in Control of Outcome by Iron(II)- And 2-Oxoglutarate-Dependent Oxygenases
Pan, Juan,Wenger, Eliott S.,Matthews, Megan L.,Pollock, Christopher J.,Bhardwaj, Minakshi,Kim, Amelia J.,Allen, Benjamin D.,Grossman, Robert B.,Krebs, Carsten,Martin Bollinger
supporting information, p. 15153 - 15165 (2019/10/19)
Iron(II)- and 2-oxoglutarate-dependent (Fe/2OG) oxygenases generate iron(IV)-oxo (ferryl) intermediates that can abstract hydrogen from aliphatic carbons (R-H). Hydroxylation proceeds by coupling of the resultant substrate radical (Ra€￠) and oxygen of the Fe(III)-OH complex ("oxygen rebound"). Nonhydroxylation outcomes result from different fates of the Fe(III)-OH/R?state; for example, halogenation results from R?coupling to a halogen ligand cis to the hydroxide. We previously suggested that halogenases control substrate-cofactor disposition to disfavor oxygen rebound and permit halogen coupling to prevail. Here, we explored the general implication that, when a ferryl intermediate can ambiguously target two substrate carbons for different outcomes, rebound to the site capable of the alternative outcome should be slower than to the adjacent, solely hydroxylated site. We evaluated this prediction for (i) the halogenase SyrB2, which exclusively hydroxylates C5 of norvaline appended to its carrier protein but can either chlorinate or hydroxylate C4 and (ii) two bifunctional enzymes that normally hydroxylate one carbon before coupling that oxygen to a second carbon (producing an oxacycle) but can, upon encountering deuterium at the first site, hydroxylate the second site instead. In all three cases, substrate hydroxylation incorporates a greater fraction of solvent-derived oxygen at the site that can also undergo the alternative outcome than at the other site, most likely reflecting an increased exchange of the initially O2-derived oxygen ligand in the longer-lived Fe(III)-OH/R?states. Suppression of rebound may thus be generally important for nonhydroxylation outcomes by these enzymes.
Preparative separation of four isomers of synthetic anisodamine by HPLC and diastereomer crystallization
Wu, Tong,Zhu, Jiu-Xin,Wei, Qian,Li, Ping,Wang, Li-Bo,Huang, Jian,Wang, Jin-Hui,Tang, Li-Ke,Wu, Li-Jun,Li, Chang,Han, Wei-Na
, p. 11 - 20 (2018/11/23)
Anisodamine (654-1), a well-known cholinergic antagonist, is marketed as synthetic anisodamine (mixture of four isomers, 654-2) in China. To preparative resolution and comparison of the bioactivities of the four isomers of synthetic anisodamine, current work explores an economic and effective separation method by using preparative high performance liquid chromatography (HPLC) and diastereomer crystallization. Their absolute configurations were established by single-crystal X-ray diffraction and circular dichroism method. The purities of each isomer were more than 95%. Among them, 654-2-A2 (6R, 2′S configuration) exhibited better effect on cabachol preconditioned small intestine tension more than 654-2 and other isomers. The direct separation method without using HPLC was tried as well, which was still on progress. This is the first report of the method for preparative separation of four isomers of synthetic anisodamine which could be used for large-scale production in industry.
Absolute configuration of natural diastereoisomers of 6β- hydroxyhyoscyamine by vibrational circular dichroism
Munoz, Marcelo A.,Munoz, Orlando,Joseph-Nathan, Pedro
, p. 1335 - 1340 (2008/12/20)
The absolute configuration of the two natural diastereoisomers of 6β-hydroxyhyoscyamine has been determined using vibrational circular dichroism (VCD) spectroscopy. The predicted VCD and IR spectra of (3R,6R,2′S)-6β-hydroxyhyoscyamine (1) and (3S,6S,2′S)-6β- hydroxyhyoscyamine (2) were calculated using density functional theory (DFT) with the B3LYP functional and 6-31G(d) basis set and considering the eight lower energy conformations of each diastereoisomer. In both cases, the first four conformers showed the N-Me group in the syn orientation, permitting the formation of a hydrogen bond between the hydroxy group at the tropane ring and the tertiary nitrogen atom. In addition the eight conformers showed an intramolecular hydrogen bond between the hydroxy and carbonyl groups of the tropic ester moiety. The calculated IR spectra of both molecules showed good agreement with the experimental spectra, while comparison of the experimental and calculated VCD spectra showed that the absolute configuration of dextrorotatory 6β-hydroxyhyoscyamine is (3R,6R,2′S), while the levorotatory isomer is (3S,6S,2′S).
