Olivier Lohse

New synthesis of oxcarbazepine via remote metalation of protected N-o-tolyl-anthranilamide derivatives

Abstract Benzyl and allyl protected N-o-tolyl-anthranilamides were efficiently prepared by Buchwald–Hartwig C–N cross coupling reactions, followed by protection of the amino group. Under directed remote metalation conditions, protected dibenzoazepinones were obtained in good yields. Deprotection of the amine and conversion to an urea furnished a new and efficient synthesis of the antiepileptic drug Trileptal®.

Application of centrifugal counter-current chromatography to the separation of macrolide antibiotic analogues: I. Selection of solvent systems based on solubility and partition coefficient investigations

As the first part of our studies on counter-current chromatography, the methodology for selecting suitable solvent systems was established based on detailed investigations of solubility and partition coefficients (log K) of macrolide antibiotic analogues. The solubility of two important macrolides, ascomycin and FK-506, was measured in a series of common solvents, where their polarities were ranked with dielectric constants. The partition coefficients of the two macrolides were compared in various binary, ternary, quaternary solvent systems. Hexane-tert.-butyl methyl ether-methanol-water system was selected based on suitable log K of solutes and hydrogen-bonding properties of solvents. In the further optimisation of composition proportions in the multicomponent solvent system, hexane-tert.-butyl methyl ether-methanol-water (1:3:6:5) showed the best solvent selectivity by giving the most prominent difference of partition coefficient (delta log K) between ascomycin and FK-506. With this solvent system, a baseline preparative separation of these two very closely related 23-membered macrolide antibiotics was successfully achieved by employing the newly introduced Quattro counter-current chromatograph.