Title: Investigation of the Bioactive Conformation of Histamine H<sub>3</sub> Receptor Antagonists by the Cyclopropylic Strain-Based Conformational Restriction Strategy
Abstract: We previously identified the highly potent histamine H3 receptor antagonists (1R,2S)-2-[2-(4-chlorobenzylamino)ethyl]-1-(1H-imidazol-4-yl)cyclopropane (1) and its enantiomer ent-1. Although the conformations of 1 and ent-1 are restricted by the central cyclopropane ring, the 2-(4-chlorobenzylamino)ethyl side chain essential for the H3 receptor binding may somewhat freely rotate. To investigate the bioactive conformation, the 1′-ethyl-substituted derivatives 2a and 2b and their enantiomers ent-2a and ent-2b were designed as side chain conformation-restricted analogues of 1 and ent-1, based on the cyclopropylic strain. These compounds were synthesized, and their analysis by NMR and calculations suggested that the side chain moiety was effectively restricted in a syn-form or an anti-form by the cyclopropylic strain as expected. Pharmacological evaluation and docking simulation showed that the bioactive conformations of 1 and ent-1 appear to be the syn-form and the anti-form, respectively. Thus, the cyclopropylic strain can be effectively used for conformational restriction of the side chain moiety of cyclopropane compounds.
Publication Year: 2010
Publication Date: 2010-04-16
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 40
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