The aim of this work was to improve the oral bioavailability of a recently discovered, novel structural class of 5-HT1A receptor agonists: aryl-{[4-(6-R-pyridin-2-ylmethyl)-amino]-methyl}- piperidin-1-yl-methanone. Incorporation of a fluorine atom in the β-position to the amino function in the side chain led to analogues that exhibited, in general, enhanced and long- lasting 5-HT1A agonist activity in rats after oral administration. Location of the fluorine ...