A series of novel indene derivatives designed by a scaffold selection gave access to several examples of (Z)-arylmethylideneindenes and indenylsulfonamides that acted as serotonin 5-HT6receptor ligands. Different synthetic multistep routes could be applied to these target compounds, each with their own complexity and limitations. A reasonable route involved the (3-indenyl)acetic acids as the key intermediates, and two alternatives were also examined. The first protocol used was a two-step sequence employing a modified Horner–Wadsworth–Emmons reaction, but better results were obtained with a procedure based on the condensation of indanones with the lithium salt of ethyl acetate, followed immediately by dehydration with acid and hydrolysis/isomerization under basic catalysis. (3-Indenyl)acetic acids were transformed to the corresponding acetamides, which were effectively reduced to indenylsulfonamides 13–17 using an optimized procedure with AlH3–NMe2Et. The binding at the 5-HT6receptor was with moderate affinity (Ki = 216.5 nM) for the (Z)-benzylideneindenylsulfonamide 12 and enhanced affinity for the simple indenylsulfonamide counterpart 13 (Ki = 50.6 nM). Selected indenylsulfonamides 14–17 were then tested, showing Ki values as low as 20.2 nM.
一系列通过选择骨架设计的新型
茚衍
生物使得获得了几种(Z)-芳基甲烯
茚和
茚基磺酰胺的例子,这些化合物作为
血清素5-HT6受体
配体。不同的合成多步路线可以应用于这些目标化合物,每种路线都有其复杂性和局限性。一条合理的路线涉及(3-
茚基)
乙酸作为关键中间体,同时还考察了两种替代方案。首先使用的是一个两步序列,采用改进的霍纳-瓦兹沃斯-埃蒙斯反应,但通过与
乙酸乙酯的
锂盐缩合,紧接着用酸脱
水和在碱催化下
水解/异构化的方法获得了更好的结果。(3-
茚基)
乙酸被转化为相应的乙酰胺,这些乙酰胺随后通过用
AlH3–NMe2Et的优化程序有效还原为
茚基磺酰胺13–17。在5-HT6受体的结合中,(Z)-苯甲烯
茚基磺酰胺12的亲和力为中等(Ki = 216.5 nM),而简单的
茚基磺酰胺13的亲和力增强(Ki = 50.6 nM)。选定的
茚基磺酰胺14–17被测试后,显示出Ki值低至20.2 nM。