A convenient synthesis of13C4-Leflunomide and its primary metabolite13C4-A77 1726

On the interactions of leflunomide and teriflunomide within receptor cavity--NMR studies and energy calculations

Leflunomide is a disease-modifying antirheumatic drug with antiinflammatory and immunosuppressive activity used for the treatment of psoriatic and rheumatoid arthritis. It undergoes rapid metabolization to teriflunomide, a metabolite that is responsible for the biological activity of leflunomide. Continuing our investigations on the interactions of biologically important azahetarenes with the environment, we focused on leflunomide and its active metabolite, teriflunomide, considering the interactions teriflunomide–amino acid within the target protein (dihydroorotate dehydrogenase) using density functional theory, as well as ONIOM techniques. The results of theoretical studies have shown that the interactions of teriflunomide with tyrosine and arginine involve principally the amide fragment of teriflunomide. The presence of the internal hydrogen bond between (Z)-teriflunomide carbonyl oxygen and enolic hydroxyl decreases the interaction strength between teriflunomide and tyrosine or arginine. Even the E isomer of teriflunomide would usually provide a stronger interaction teriflunomide—amino acid than the Z isomer with the internal hydrogen bond.

Graphical Abstract

NIS-mediated oxidative cyclization of N-(2-trifluoromethyl-3-alkynyl) hydroxylamines: a facile access to 4-trifluoromethyl-5-acylisoxazoles

A NIS mediated sequential procedure involving oxidation and electrophilic cycloisomerization ofN-(2-trifluoromethyl-3-alkynyl) hydroxylamines for 4-trifluoromethyl-5-acylisoxazole synthesis is developed.

13C bis-labeled pyrroles: A tool for the identification of the rat metabolism of 3-methyl pyrrole-2,4-dicarboxylic acid 2-propyl ester 4-(1,2,2-trimethyl-propyl) ester

Following the recent disclosure of 3-methyl pyrrole-2,4-dicarboxylic acid 2-propyl ester 4-(1,2,2-trimethyl-propyl) ester as a potent and selective mGluR1 non-competitive antagonist, the use of a doubly (13)C-labeled analogue to identify, and consequently prevent, metabolically labile positions is reported.