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in Wiley InterScience (www.interscience.wiley.com).The addition reaction of lithium reagents to the 4 position of 2-chloropyrimidine or 2-chloroquinazoline followed by oxidation of the resultant dihydro intermediate product is a powerful tool for the synthesis of 4-substituted 2-chloropyrimidines or 2-chloroquinazolines. 4-Vinyl derivatives undergo a conjugate nucleophilic addition across the vinyl group. A nucleophilic displacement of chloride in 4-substituted 2-chloropyrimidines or 2-chloroquinazolines by treatment with 4-methylpiperazine provides compounds that are antagonists of the serotonin 5-HT 2A receptor.

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An efficient solid-supported method for the synthesis of a new class of arylpiperazine derivatives containing amino acid residues has been developed. A 72-membered library was synthesized on SynPhase Lanterns functionalized by a BAL linker. A one-pot cleavage/cyclization step of aspartic and glutamic acid derivatives yielded succinimide- and pyroglutamyl-containing ligands (chemsets 9 and 10). The library representatives under study showed different levels of affinity for 5-HT(1A) and 5-HT(2A) receptors (estimated K(i) = 24-4000 and 1-2130 nM, respectively). Several dual 5-HT(1A)/5-HT(2A) ligands were found, of which two (9(3,3) and 9(3,5)) displayed high 5-HT(2A) affinity comparable to that of the reference drug ritanserin. A set of individual fragment contributions for the prediction of 5-HT(1A) and 5-HT(2A) affinity of all the library members were defined on the basis of the Free-Wilson analysis of 26 compounds. An alkylarylpiperazine fragment had essentially the same impact on the affinity for both receptors, whereas different terminal amide fragments were preferred by 5-HT(1A) (chemset 17, R(2) = adamantyl) and 5-HT(2A) (chemset 9, R(2) = norborn-2-ylmethyl) binding sites.