Thiophene Bioisosteres of Spirocyclic σ Receptor Ligands. 1. N-Substituted Spiro[piperidine-4,4′-thieno[3,2-<i>c</i>]pyrans]
作者:Christoph Oberdorf、Dirk Schepmann、Jose Miguel Vela、Jose Luis Diaz、Jörg Holenz、Bernhard Wünsch
DOI:10.1021/jm8007739
日期:2008.10.23
Herein, the synthesis and pharmacological evaluation of thiophene bioisosteres of the highly potent spirocyclic benzopyran 1 are detailed. The synthesis of 1-benzyl-6'-methoxy-6',7'-dihydrospiro[piperidine-4,4'-thieno[3.2-c]pyran] (2a) was performed starting with 3-bromothiophene (3). After introduction of the acetaldehyde substructure (7), halogen metal exchange, addition of 1-benzylpiperidin-4-one, and cyclization led to the spirocyclic thienopyran 2a. The removal of the benzyl group afforded the secondary amine 2f, which was substituted with various residues. With respect to a, affinity the N-benzyl derivative 2a, the N-cyclohexylmethyl derivative 2d, and the N-p-fluorobenzyl derivative 2i represent the most potent compounds of this series binding with K-i values of 0.32, 0.29, and 0.62 nM, respectively. Electronic properties of the substituents have only little impact on sigma(1) affinity. The most potent sigma(1) ligands display high selectivity against sigma(2), 5-HT1A, 5-HT6, 5-HT7, alpha(1A), alpha(2), and NMDA receptors. The activity of 2a in the mouse capsaicin assay seems to indicate sigma(1) antagonistic activity.