56613-81-1Relevant articles and documents
Two enantiocomplementary ephedrine dehydrogenases from arthrobacter sp. TS-15 with broad substrate specificity
Shanati, Tarek,Lockie, Cameron,Beloti, Lilian,Grogan, Gideon,Ansorge-Schumacher, Marion B.
, p. 6202 - 6211 (2019/08/15)
The recently identified pseudoephedrine and ephedrine dehydrogenases (PseDH and EDH, respectively) from Arthrobacter sp. TS-15 are NADH-dependent members of the oxidoreductase superfamily of short-chain dehydrogenases/reductases (SDRs). They are specific for the enantioselective oxidation of (+)-(S) N-(pseudo)ephedrine and (-)-(R) N-(pseudo)ephedrine, respectively. Anti-Prelog stereospecific PseDH and Prelog-specific EDH catalyze the regio- A nd enantiospecific reduction of 1-phenyl-1,2-propanedione to (S)-phenylacetylcarbinol and (R)-phenylacetylcarbinol with full conversion and enantiomeric excess of >99%. Moreover, they perform the reduction of a wide range of aryl-aliphatic carbonyl compounds, including ketoamines, ketoesters, and haloketones, to the corresponding enantiopure alcohols. The highest stability of PseDH and EDH was determined to be at a pH range of 6.0-8.0 and 7.5-8.5, respectively. PseDH was more stable than EDH at 25 °C with half-lives of 279 and 38 h, respectively. However, EDH is more stable at 40 °C with a 2-fold greater half-life than at 25 °C. The crystal structure of the PseDH-NAD+ complex, refined to a resolution of 1.83 ?, revealed a tetrameric structure, which was confirmed by solution studies. A model of the active site in complex with NAD+ and 1-phenyl-1,2-propanedione suggested key roles for S143 and W152 in recognition of the substrate and positioning for the reduction reaction. The wide substrate spectrum of these dehydrogenases, combined with their regio- A nd enantioselectivity, suggests a high potential for the industrial production of valuable chiral compounds.
Highly efficient enantioselective liquid-liquid extraction of 1,2-amino-alcohols using SPINOL based phosphoric acid hosts
Pinxterhuis, Erik B.,Gualtierotti, Jean-Baptiste,Heeres, Hero J.,De Vries, Johannes G.,Feringa, Ben L.
, p. 6409 - 6418 (2017/08/29)
Access to enantiopure compounds on large scale in an environmentally friendly and cost-efficient manner remains one of the greatest challenges in chemistry. Resolution of racemates using enantioselective liquid-liquid extraction has great potential to meet that challenge. However, a relatively feeble understanding of the chemical principles and physical properties behind this technique has hampered the development of hosts possessing sufficient resolving power for their application to large scale processes. Herein we present, employing the previously untested SPINOL based phosphoric acids host family, an in depths study of the parameters affecting the efficiency of the resolution of amino-alcohols in the optic of further understanding the core principles behind ELLE. We have systematically investigated the dependencies of the enantioselection by parameters such as the choice of solvent, the temperature, as well as the pH and bring to light many previously unsuspected and highly intriguing interactions. Furthermore, utilizing these new insights to our advantage, we developed novel, highly efficient, extraction and resolving protocols which provide remarkable levels of enantioselectivity. It was shown that the extraction is catalytic in host by demonstrating transport in a U-tube and finally it was demonstrated how the solvent dependency could be exploited in an unprecedented triphasic resolution system.
Heterogenization of chiral mono oxazoline ligands by grafting onto mesoporous silica MCM-41 and their application in copper-catalyzed asymmetric allylic oxidation of cyclic olefins
Samadi, Saadi,Jadidi, Khosrow,Khanmohammadi, Behnam,Tavakoli, Niloofar
, p. 344 - 353 (2016/07/06)
A series of chiral 4-oxazolinylaniline ligands 8 were conveniently synthesized on a gram scale from inexpensive and commercially available 4-aminobenzoic acid in four steps. The obtained organic chiral ligands have been covalently grafted onto ordered mesoporous silicas MCM-41 and the resulting inorganic–organic hybrid materials have been characterized by thermogravimetric analysis (TGA), differential thermal analysis (DTA), powder X-ray diffraction, BET and BJH nitrogen adsorption–desorption methods, energy-dispersive X-ray spectroscopy (EDX), CHN analysis, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR). The catalytic and induced asymmetric effects of the chiral copper (I) complexes of these new chiral supported heterogeneous catalysts on the asymmetric allylic oxidation of cycloolefins were investigated under different conditions. Reactions using the catalyst exhibited moderate to good enantioselectivities, up to 80%, and good yields, up to 95% better than the corresponding homogeneous reaction. The catalyst could be recovered easily and reused five times without remarkable loss of reactivity, yield, or enantioselectivity. This is, to the best of our knowledge, the first heterogenization of chiral 4-oxazolinylaniline ligands on an inorganic (silica) surface and their application as a heterogeneous catalyst in the asymmetric Kharash–Sosnovsky reaction.
