321-97-1Relevant articles and documents
Chiral Manganese Aminopyridine Complexes: the Versatile Catalysts of Chemo- and Stereoselective Oxidations with H2O2
Ottenbacher, Roman V.,Talsi, Evgenii P.,Bryliakov, Konstantin P.
, p. 78 - 90 (2017/10/06)
In the last decade, manganese(II) complexes with N-donor tetradentate aminopyridine ligands emerged as efficient catalysts of enantioselective epoxidation of olefins and direct selective oxidation of C?H groups in complex organic molecules, with environmentally benign oxidant hydrogen peroxide. In this personal account, we summarize the progress of these catalysts with regard to ligands design, structure-reactivity correlations, evaluation of the substrate scope, as well as mechanistic studies, shedding light on the nature of active sites and the mechanisms of selective oxygenations. Several practically promising catalytic syntheses with the aid of Mn aminopyridine catalysts are exemplified.
Measurement of stable isotope ratios in methylamphetamine: A link to its precursor source
Salouros, Helen,Sutton, Gordon J.,Howes, Joanna,Hibbert, D. Brynn,Collins, Michael
, p. 9400 - 9408 (2013/10/21)
The illicit drug methylamphetamine is often prepared from the precursor ephedrine or pseudoephedrine, which in turn are obtained by three processes: extraction from the Ephedra plant ("natural"), via fermentation of sugars ("semi-synthetic"), and by a "fully synthetic" route from propiophenone. We report the first method to differentiate between the three industrial routes used to produce the precursors ephedrine and pseudoephedrine by measurement of stable isotope ratios of nitrogen (δ15N), hydrogen (δ2H), and carbon (δ13C). Analysis of 782 samples of seized methylamphetamine allowed classification into three groups using k-means clustering or the expectation-maximization algorithm applied to a Gaussian mixture model. By preparation of 30 samples of ephedrine by the "fully synthetic" industrial process and measuring their δ15N, δ2H, and δ13C values, we observed that 15N becomes significantly depleted compared to the methylamine starting material. Conversion of ten ephedrine samples to methylamphetamine showed that this depletion is maintained in the final drug product, of which the δ15N, δ13C, and δ2H values were distinct from those of ephedrine and methylamphetamine samples of a semi-synthetic (fermentation pathway) origin. Combining modeling analysis with the new experiments and published information on the values of δ2H gave a definitive assignment of the three model groups, and equations to obtain probabilities for the precursor origin of any new sample. A simple rule of thumb is also presented. Making an assignment using delta values is particularly useful when no other chemical profiling information is available.
Polymer-immobilized catalyst for asymmetric hydrogenation of racemic α-(N-benzoyl-N-methylamino)propiophenone
Chiwara, Vinia Ipai,Haraguchi, Naoki,Itsuno, Shinichi
body text, p. 1391 - 1393 (2009/07/04)
Asymmetric hydrogenation of α-(N-benzoyl-N-methylami-no)propiophenone through dynamic kinetic resolution was performed by using a polymer-immobilized chiral diamine-ruthenium-BINAP-t-BuOK system in order to yield syn-β-amidealcoholexclusivelywithnearlyperfectenantioselectivity.