No abstract

In 2000, three research groups demonstrated that the widely held view that chiral bidentate ligands are necessary to achieve high enantioselectivity in rhodium-catalyzed hydrogenations needs revision. Monodentate phosphonites, [1a] phosphites [1b] and phosphoramidites [1c] proved to be highly versatile ligands for this important transformation and afforded excellent enantioselectivities for a broad range of substrates.

High turnover enantioselective alkene cis-dihydroxylation is achieved with H(2)O(2) catalysed by manganese based complexes containing chiral carboxylato ligands.

Citation for published version (APA): Dalmolen, J., Tiemersma-Wegman, TD., Nieuwenhuijzen, JW., van der Sluis, M., van Echten, E., Vries, TR., ... Broxterman, Q. B. (2005). The Dutch resolution variant of the classical resolution of racemates by formation of diastereomeric salts: Family behaviour in nucleation inhibition. Chemistry, 11(19), 5619-5624.

[ 18 F]MPPF is a selective serotonin-1A (5-HT 1A ) receptor antagonist and may be used to measure changes in the functional levels of serotonin (5-HT). The technique is based on the assumption that the injected radiolabeled ligand competes for the same receptor as the endogenous transmitter. Results from studies using serotonergic ligands are not always consistent. The aim of the present study was to investigate if [18 F]MPPF binding is decreased after an increase in 5-HT levels.[ 18 F]MPPF binding was assessed in conscious rats using ex vivo autoradiography. We studied the effect of the 5-HT-releasing agent and reuptake inhibitor fenfluramine (10 mg/kg i.p.) and of a combination of the selective serotonin reuptake inhibitor (SSRI) citalopram (10 mmol/kg, s.c.) with the 5-HT 2C antagonist ketanserin (100 nmol/kg, s.c). The effect of both treatments on extracellular 5-HT levels was determined using microdialysis. Fenfluramine treatment resulted in a 30-fold increase in extracellular 5-HT levels in the ventral hippocampus and induced a significant reduction of [18 F]MPPF binding in the frontal cortex, hypothalamus, amygdala, and hippocampus. The microdialysis results showed a 10-fold 5-HT increase in the ventral hippocampus after combined administration of ketanserin and citalopram. The combination, however, did not affect [18 F]MPPF binding. Our data show that [18 F]MPPF binding in conscious rats is only reduced after substantial and therefore nonphysiological increases in 5-HT levels. These results may imply that the majority of 5-HT 1A receptors is in the low-affinity state, in vivo.