1.Concentration dependence of biotransformation in fish liver S9: Optimizing substrate concentrations to estimate hepatic clearance for bioaccumulation assessment.
Lo JC1, Allard GN2, Otton SV2, Campbell DA3, Gobas FA1,2. Environ Toxicol Chem. 2015 Dec;34(12):2782-90. doi: 10.1002/etc.3117. Epub 2015 Oct 15.
In vitro bioassays to estimate biotransformation rate constants of contaminants in fish are currently being investigated to improve bioaccumulation assessments of hydrophobic contaminants. The present study investigates the relationship between chemical substrate concentration and in vitro biotransformation rate of 4 environmental contaminants (9-methylanthracene, pyrene, chrysene, and benzo[a]pyrene) in rainbow trout (Oncorhynchus mykiss) liver S9 fractions and methods to determine maximum first-order biotransformation rate constants. Substrate depletion experiments using a series of initial substrate concentrations showed that in vitro biotransformation rates exhibit strong concentration dependence, consistent with a Michaelis-Menten kinetic model. The results indicate that depletion rate constants measured at initial substrate concentrations of 1 μM (a current convention) could underestimate the in vitro biotransformation potential and may cause bioconcentration factors to be overestimated if in vitro biotransformation rates are used to assess bioconcentration factors in fish.
2.Application of singular value decomposition analysis to time-dependent powder diffraction data of an in-situ photodimerization reaction.
Mabied AF1, Nozawa S2, Hoshino M3, Tomita A2, Sato T2, Adachi SI2. J Synchrotron Radiat. 2014 May;21(Pt 3):554-60. doi: 10.1107/S1600577514004366. Epub 2014 Apr 2.
Singular value decomposition (SVD) analysis has important applications for time-dependent crystallographic data, extracting significant information. Herein, a successful application of SVD analysis of time-resolved powder diffraction data over the course of an in-situ photodimerization reaction of anthracene derivatives is introduced. SVD revealed significant results in the case of 9-methylanthracene and 1-chloroanthracene. The results support the formation of the 9-methylanthracene stable dimer phase and suggest the existence of an excimer state.
3.CH3-deprotonation of 9-methylanthracene under mild conditions.
Finkelmeier N1, Visscher A1, Wandtke S1, Herbst-Irmer R1, Stalke D1. Chem Commun (Camb). 2016 Apr 7;52(31):5440-2. doi: 10.1039/c6cc01261b.
The chromophore building-block 9-methylanthracene is selectively deprotonated at the methyl group and activated for reactions with electrophiles.
4.Synthesis and resolution of the biaryl-like diphosphine (S)-Me2-CATPHOS, preparation of a derived rhodium precatalyst and applications in asymmetric hydrogenation.
Doherty S1, Smyth CH. Nat Protoc. 2012 Oct;7(10):1884-96. doi: 10.1038/nprot.2012.108. Epub 2012 Sep 20.
This protocol describes the synthesis of a representative example of the enantiopure biaryl-like CATPHOS class of diphosphines, (S)-9,9'-dimethyl-9,9',10,10'-tetrahydro-9,10,9',10'-biethenobianthracene-11,11'-bis(diphenylphosphino)-12,12'-diyl ((S)-Me(2)-CATPHOS), and its derived cationic rhodium-based hydrogenation precatalyst. The C(2)-symmetric framework of Me(2)-CATPHOS is the result of a regioselective Diels-Alder cycloaddition between 1,4-bis(diphenylphosphinoyl)buta-1,3-diyne and 9-methylanthracene, such that the bulky methyl-substituted bridgehead carbon atoms are attached to C2 and C3 of the 1,3-butadiene tether. Enantiopure Me(2)-CATPHOS is obtained in an operationally straightforward three-step procedure and isolated in ∼50-60% overall yield and <99% enantiopurity, after diastereoselective resolution with (2R,3R)-(-)-2,3-O-dibenzoyltartaric acid. The derived rhodium complex forms a highly effective catalyst for the asymmetric hydrogenation of a range of dehydroamino acid derivatives, as well as (E)-β-aryl-(enamido)phosphonates, giving ee values in excess of 99%, the highest to be reported for the latter class of substrate.