The synthesis of three racemates and the corresponding non chiral analogues of a C5-methyl pyridazine series is described here, as well as the isolation of pure enantiomers and their absolute configuration assignment. In order to obtain optically active compounds, direct chromatographic methods of separation by HPLC-UV were investigated using four chiral stationary phases (CSPs: Lux Amylose-2®, Lux Cellulose-1®, Lux Cellulose-2® and Lux Cellulose-3®). The best resolution was achieved using amylose tris(5-chloro-2-methylphenylcarbamate) (Lux Amylose-2®), and single enantiomers were isolated on a semipreparative scale with high enantiomeric excess, suitable for biological assays. The absolute configuration of optically active compounds was unequivocally established by X-ray crystallographic analysis and comparative chiral HPLC-UV profile. All compounds of the series were tested for formyl peptide receptor (FPR) agonist activity, and four were found to be active, with EC50 values in the micromolar range.
A rapid, highly sensitive method is described for the spectrographic determination of boron in nuclear-grade graphite. Boron, present in the sample in the form of boron carbide (B4C), is volatilised as the trifluoride by the addition of 1 per cent. of Kel-F powder (polychlorotrifluoroethylene) to the samples. The samples, containing 600 p.p.m. of silicon as the internal standard, are excited by a 10-A d.c. arc in the presence of an argon-controlled atmosphere. A linear relationship between the intensity ratio of the lines boron 249.773nm and silicon 245.214nm and the boron concentration is established in the boron concentration range 0.1 to 5 p.p.m. The relative standard deviation, calculated from twelve determinations on each sample, ranges from AS per cent. (at 5 p.p.m. of boron) to &11 per cent. (at 0-1 p.p.m. of boron).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.