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Issue 19, 1999
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Synthesis and serotonergic activity of a series of 2-(N-benzyl)carboxamido-5-substituted-N,N-dimethyltryptamine derivatives: novel antagonists for the vascular 5-HT1B-like receptors

Abstract

The synthesis and vascular 5-HT1B-like receptor activity of a novel series of 2-(N-benzyl)carboxamido-5-substituted-N,N-dimethyltryptamine derivatives is described. Modifications to the 5-ethylene linked heterocycle are explored. Compounds such as N-benzyl-5-[2-(phthalimido)ethyl]-3-[2-(dimethylamino)ethyl]-1H-indole-2-carboxamide 22 (pKB = 7.33), the 2-aminobenzyl analogue 24 (pKB = 7.19), which both contain a phthalimide group, and N-benzyl-5-[2-(1-benzyl-2,5-dioxoimidazolidin-4-yl)ethyl]-3-[2-(dimethylamino)ethyl]-1H-indole-2-carboxamide 81 (pKB = 7.05), which incorporates an N-benzylhydantoin moiety, have good 5-HT1B-like affinity and indicate that there may be a hydrophobic binding pocket within the vascular 5-HT1B-like receptor previously not considered. Compounds including N-benzyl-3-[2-(dimethylamino)ethyl]-5-[2-(2,4-dioxo-1,3-thiazolidinyl)ethyl]-1H-indole-2-carboxamide 39 (pKB = 7.35) and the dimethyl analogue 46 (pKB = 7.48) which contain a 2,4-thiazolidinedione moiety have good vascular 5-HT1B-like receptor affinity and show that the sulfur atom is well tolerated. Compound 61 which includes a methylsulfonyl substituent on the 1-nitrogen of the hydantoin ring system has the highest recorded 5-HT1B-like affinity for this series (pKB = 7.54) and it is proposed that this functional group can interact with a secondary hydrogen bonding region within the receptor. Compounds 22, 24, 39, 46, 61 and 81 also exhibited good selectivity over the α1-adrenoceptors. The most selective compound from this series is 46 which contains a 5,5-dimethylthiazolidine-2,4-dione group and which is 66-fold selective over the α1-adrenoceptors. This finding is consistent with the previous discovery that 5,5-dimethyl substitution on the hydantoin group in a related series of compounds afforded superior selectivity for 5-HT1B-like receptors over α1-adrenoceptors and other 5-HT receptors, in particular 5-HT2A receptors, relative to unsubstituted hydantoin analogues. The selectivity of these compounds for the vascular 5-HT1B-like receptor is discussed. Structure–activity relationship indicated a significant steric requirement of the 5-HT1B-like receptor subtype. Potential modes of binding for several of the compounds to a vascular 5-HT1B-like receptor pharmacophore model are also proposed.

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Article information


J. Chem. Soc., Perkin Trans. 1, 1999, 2699-2711
Article type
Paper

Synthesis and serotonergic activity of a series of 2-(N-benzyl)carboxamido-5-substituted-N,N-dimethyltryptamine derivatives: novel antagonists for the vascular 5-HT1B-like receptors

G. P. Moloney, G. R. Martin, N. Mathews, H. Hobbs, S. Dodsworth, P. Yih Sang, C. Knight, M. Maxwell and R. C. Glen, J. Chem. Soc., Perkin Trans. 1, 1999, 2699
DOI: 10.1039/A903141C

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