Synthesis and Radioligand Binding Studies of Methoxylated 1,2,3,4-Tetrahydroisoquinolinium Derivatives as Ligands of the Apamin-Sensitive Ca2+-Activated K+ Channels
摘要:
Several methoxylated 1,2,3,4-tetrahydroisoquinoliniums derived from N-methyl-laudanosine and N-methyl-noscapine were synthesized and evaluated for their affinity for apamin-sensitive binding sites. The quaternary ammonium derivatives have a higher affinity with regard to the tertiary amines. 6,7-Dimethoxy analogues possess a higher affinity than the 6,8- and 7,8- dimethoxy isomers. A 3,4-dimethoxybenzyl or a 2-naphthylmethyl moiety in C-1 position are more favorable than a 3,4-dimethoxyphenethyl group. Smaller groups such as propyl or isobutyl are unfavorable. In 6,7-dimethoxy analogues, increasing the size and lipophilicity with a naphthyl group in the C-1 position leads to a slight increase of affinity, while the same group in the 6,7,8- trimethoxy series is less favorable. The 6,7,8- trimethoxy derivative 3f is the first tertiary amine in the series to possess an affinity close to that of N-methyl-laudanosine and N-methyl-noscapine. Moreover, electrophysiological studies show that the most effective compound 4f blocks the apamin-sensitive afterhyperpolarization in rat dopaminergic neurons.
Dihydroisochinolinumlagerung, 38. Mitt. Verhalten von 1,2-Dihydroisochinolinen mit sperrigen C-1-Substituenten gegen Säuren
作者:Joachim Knabe、Franz-Josef Grünewald
DOI:10.1002/ardp.19873200604
日期:——
Die aus den Iminiumsalzen 1a‐1d durch Reduktion mit LiAlH4 erhaltenen 1,2‐Dihydroisochinoline 2a‐2d werden mit verdünnten Säuren erhitzt. Dabei erleiden 2a und 2b in 44proz. Ausbeute Umlagerung zu 3a und 3b, 2c in 17proz. Ausbeute zu 3c. 2d wird unter den angewandten Reaktionsbedingungen nicht umgelagert, es wird größtenteils unverändert zurückgewonnen. Bei der Umsetzungvon 2b wird als Eliminierungsprodukt