Synthesis and biological evaluation of new non-imidazole H3-receptor antagonists of the 2-aminobenzimidazole series
摘要:
A novel series of non-imidazole H-3-receptor antagonists was developed, by chemical modification of a potent lead H-3-antagonist composed by an imidazole ring connected through an alkyl spacer to a 2-aminobenzimidazole moiety (e.g., 2-[[3-[4(5)-imidazolyl]propyl]amino]benzimidazole), previously reported by our research group. We investigated whether the removal of the imidazole ring could allow retaining high affinity for the H-3-receptor, thanks to the interactions undertaken by the 2-aminobenzimidazole moiety at the binding site. The imidazole ring of the lead was replaced by a basic piperidine or by a lipophilic p-chlorophenoxy substituent, modulating the spacer length from three to eight methylene groups; moreover, the substituents were moved to the 5(6) position of the benzimidazole nucleus. Within both the 2-alkylaminobenzimidazole series and the 5(6)-alkoxy-2-amino-benzimidazole one, the greatest H-3-receptor affinity was obtained for the piperidine-substituted compounds, while the presence of the p-chlorophenoxy group resulted in a drop in affinity. The optimal chain length was different in the two series. Even if the new compounds did not reach the high receptor affinity shown by the imidazole-containing lead compound, it was possible to get good H-3-antagonist potencies with 2-aminobenzimidazoles having a tertiary amino group at appropriate distance. (c) 2005 Elsevier Ltd. All rights reserved.
研究了分子内亲核芳族取代反应(称为Truce-Smiles重排)中底物中强电子吸收取代基对芳环活化的要求。初步的力学实验支持S N Ar机理,包括原位形成的Meisenheimer中间体的1 H和13 C NMR光谱。通常观察到重排对于具有强吸电子取代基(例如硝基,氰基和苯甲酰基官能团)的底物是成功的,但对于具有多个弱吸电子取代基(例如氯和溴官能团)的底物也是如此组。这些结果提供进一步的澄清的芳基取代基在这种类型的S的影响Ñ的Ar反应。另外,该调查还揭示了某些底物进行的一些串联环化和/或消除反应。
Ligand-Free, Palladium-Catalyzed Dihydrogen Generation from TMDS: Dehalogenation of Aryl Halides on Water
作者:Anish Bhattacharjya、Piyatida Klumphu、Bruce H. Lipshutz
DOI:10.1021/ol5037369
日期:2015.3.6
A mild and environmentally attractive dehalogenation of functionalized aryl halides has been developed using nanoparticles formed from PdCl2 in the presence of tetramethyldisiloxane (TMDS) on water. The active catalyst and reaction medium can be recycled. This method can also be applied to cascade reactions in a one-pot sequence.