Orthogonal analytical screening for liquid chromatography-mass spectrometry method development and preparative scale-up.

An analytical HPLC-MS screening methodology has been developed to improve preparative RP-HPLC-MS purifications in medicinal chemistry laboratories. Although several approaches have been previously described to optimize analytical separations, none of them met our needs for the optimization of preparative conditions. Our screening protocol is based on searching among several orthogonal conditions to find the optimum preparative separation. Five different buffer conditions, from low to high pH, two organic solvents, acetonitrile and methanol, and five stationary phases of different polarities and characteristics were used. The orthogonality of the system was demonstrated using both, a standard mixture and mixtures from synthesis. To carry out the screening one of the analytical "open access" HPLC-MS systems was modified to perform the analytical screening while maintaining the open-access functionality for synthesis reaction monitoring. A software tool for automated sample programming and data reporting was also developed.

Tricyclic isoxazolines: identification of R226161 as a potential new antidepressant that combines potent serotonin reuptake inhibition and alpha2-adrenoceptor antagonism.

In previous articles we have described the discovery of a new series of tricyclic isoxazolines combining central serotonin (5-HT) reuptake inhibition with alpha(2)-adrenoceptor antagonistic activity. We report now on the synthesis, the in vitro binding potency and the primary in vivo activity of six enantiomers within this series, one of which was selected for further pharmacological evaluation and assigned as R226161. Some additional in vivo studies in rats are described with this compound, which proved to be centrally and orally active as a combined 5-HT reuptake inhibitor and alpha(2)-adrenoceptor antagonist.

Discovery of a new series of centrally active tricyclic isoxazoles combining serotonin (5-HT) reuptake inhibition with alpha2-adrenoceptor blocking activity.

The synthesis and pharmacology of a new series of 3-piperazinylmethyl-3a,4-dihydro-3H-[1]benzopyrano[4,3-c]isoxazoles that combine central serotonin (5-HT) reuptake inhibition with alpha(2)-adrenoceptor blocking activity is described as potential antidepressants. Four compounds were selected for further evaluation, and the combination of both activities was found to be stereoselective, residing mainly in one enantiomer. Reversal of the loss of righting induced by the alpha(2)-agonist medetomidine in rats confirmed the alpha(2)-adrenoceptor blocking activity in vivo and also demonstrated CNS penetration. Antagonism of p-chloroamphetamine (pCA)-induced excitation as well as blockade of the neuronal 5-HT depletion induced by p-CA administration in rats confirmed their ability to block the central 5-HTT, even after oral administration. Replacement of the oxygen atom at the 5-position of the tricyclic scaffold by a nitrogen or a carbon atom, as well as O-substitution at position 7, led also to active compounds, both in vitro and in vivo.

Synthesis of 3a,4-dihydro-3H-[1]benzopyrano[4,3-c]isoxazoles, displaying combined 5-HT uptake inhibiting and alpha2-adrenoceptor antagonistic activities. Part 2: Further exploration on the cinnamyl moiety.

In our previous paper we have described the synthesis of a series of 3-piperazinylmethyl-3a,4-dihydro-3H-[1]benzopyrano[4,3-c]isoxazoles, as novel dual 5-HT reuptake inhibitors and alpha2-adrenoceptor antagonists. That investigation led to the identification of the cinnamyl fragment as the most suitable moiety for combined activity. This paper outlines a further optimisation programme, focused on the exploration of the aromatic ring present on the cinnamyl moiety of compounds 1, 2 and 3.