In this study, the impact of one or two hydroxy moieties at the benzo[7]annulene scaffold on the GluN2B affinity and cytoprotective activity was analyzed. The key intermediate for the synthesis of OH-substituted benzo[7]annulenamines 11-13 and 17 was the epoxyketone 8. Reductive epoxide opening of 8 resulted with high regioselectivity in the 5-hydroxyketone 9 (Pd(OAc)₂, HCO₂H, phosphane ligand) or the 6-hydroxyketone 10 (H₂, Pd/C), whereas hydrolysis in aqueous dioxane led to the dihydroxyketone 14. Reductive amination of these ketones with primary amines and NaBH(OAc)₃ afforded the benzo[7]annulenamines 11-13 and 17. In receptor binding studies 5-OH derivatives 11 and 12 showed higher GluN2B affinity than 6-OH derivatives 13, which in turn were more active than 5,6-di-OH derivative 17a. The same order was found for the cytoprotective activity of the ligands. The tertiary amine 12a with one OH moiety in 5-position represents the most promising GluN2B negative allosteric modulator with a binding affinity of K_i = 49 nM and a cytoprotective activity of IC₅₀ = 580 nM. In the binding pocket 12a shows a crucial H-bond between the benzylic OH moiety and the backbone carbonyl O-atom of Ser132 (GluN1b). It was concluded that a 5-OH moiety is essential for the inhibition of the NMDA receptor associated ion channel, whereas a OH moiety in 6-position is detrimental for binding and inhibition. An OH or CH₂OH moiety at 2-position results in binding at the ifenprodil binding site, but very weak ion channel inhibition.

在这项研究中，分析了苯并[7]环戊烯骨架上一个或两个羟基对GluN2B亲和力和细胞保护活性的影响。为OH取代的苯并[7]的合成中间体的关键annulenamines 11 - 13和17是环氧酮8。在5-羟基酮9（Pd（OAc）₂，HCO ₂ H，膦配体）或6-羟基酮10（H ₂，Pd / C）中，还原环氧化物8的开环具有较高的区域选择性，而在二恶烷水溶液中的水解则导致二羟基酮14。这些酮与伯胺和NaBH（OAc）的还原性胺化₃得到苯并[7] annulenamines 11 - 13和17。在受体结合研究中，5-OH衍生物11和12显示出比6-OH衍生物13高的GluN2B亲和力，而6-OH衍生物13则比5,6-di-OH衍生物17a更具活性。对于配体的细胞保护活性，发现了相同的顺序。在5位上带有一个OH部分的叔胺12a代表最有希望的GluN2B负变构调节剂，其结合亲和力为K _i = 49 nM，细胞保护活性为IC ₅₀ = 580 nM。在结合口袋12a中，在苄基OH部分和Ser132（GluN1b）的骨架羰基O原子之间显示了关键的H键。结论是5-OH部分对于抑制NMDA受体相关的离子通道是必不可少的，而6-位的OH部分对于结合和抑制是有害的。在2位的OH或CH ₂ OH部分导致在艾芬地尔的结合位点结合，但对离子通道的抑制作用非常弱。