- (8β)-6-Methylergoline amide derivatives as serotonin antagonists: N1-substituent effects on vascular 5HT2 receptor activity
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A series of (8β)-6-methylergoline amide derivatives was synthesized with various alkyl substituents in the N1-position in order to evaluate their effectiveness in blocking vascular 5HT2 receptors. The influence of both the N1 substituent and amide derivative proved to be of great importance on binding affinities to vascular 5HT2 receptors. Within each series of amides, however, maximum affinity was achieved with an N1-isopropyl substituent (14, 18, 26, 38, and 41; all with 2.7-5.0 times greater affinity than their N1-H analogues), with the exception of two cases (22 and 37) in the cyclohexylamide derivatives wherein N1-methyl equalled the isopropyl in potency. Other than these exceptions, affinities followed the pattern of H Me Et iPr, with potencies falling off with larger alkyl substituents.
- Misner,Garbrecht,Marzoni,Whitten,Cohen
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p. 652 - 656
(2007/10/02)
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- Stereochemistry of Alkylation of Carboxylic Acid Salt and Ester α Anions Derived from Cyclic Systems.
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A stereochemical study of the alkylation of α-lithiated carboxylate salts and esters has been performed.The α anions derived from the bicyclic acids exo-1, endo-1, and 7 (R=H) and the esters 4 and 7 (R=CH3) yield predominantly exo alkylation.As an example, the α anion derived from ester 7 (R=CH3) on treatment with CH3I yields exo-8 (R=R'=CH3) and endo-9 (R=R'=CH3) in a 97:3 ratio, a highly stereoselective reaction.Addition of TMEDA to the reactions involving the α anions derived from exo- or endo-1 did not change the stereochemical alkylation results.The α anions derived from the substituted cyclohexanecarboxylic acids 10, 13, 16, 19, or 22 (where R=H in each case) on methylation yield more axial methylation (axial/equatorial ratios of 0.4-2.7) than the α anions derived from the methyl esters corresponding to these acids.The α anions from the esters yield predominantly equatorial methylated products (e/a ratios varying from 4 to 9).The reasons for the different stereochemical results are discussed.
- Krapcho, A.Paul,Dundulis, Edward A.
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p. 3236 - 3245
(2007/10/02)
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