An Improved Synthesis and Structural Characterisation of 2-(4-Acetylthiophenylethynyl)-4-nitro-5-phenylethynylaniline: The Molecule Showing High Negative Differential Resistance (NDR)
作者:Martin R. Bryce、Changsheng Wang、Andrei S. Batsanov、Ian Sage
DOI:10.1055/s-2003-41451
日期:——
2-(4-Acetylthiophenylethynyl)-4-nitro-5-phenyl-ethynyl-aniline (11) has been synthesised by an improved route, which has many advantages over the literature procedure. A key intermediate is 2-ethynyl-4-nitro-5-phenylethynylaniline (6) which is obtained from 2,5-dibromoacetanilide (5 steps, 68% overall yield). Reaction of 6 with 1-acetylthio-4-iodobenzene under Sonogashira coupling conditions affords 11 (56%). Compound 11 is characterised by CHN analysis, mass spectrometry and 1H and 13C NMR spectroscopy. The crystal structures of 2-bromo-4-nitro-5-phenylethynylaniline (4), 2-(3-hydroxy-3-methylbutynyl)-4-nitro-5-phenylethynylaniline (5) and 2-[(4-methoxybenzylthio)phenylethynyl]-4-nitro-5-phenylethynylaniline (15), have been determined, by which the regiochemical structure of 11 is also proved. The intramolecular contacts O(1)···C(7) of 2.692(2) Å in 4 and 2.677(2) Å in 15 are considerably shorter than the standard van der Waals O···C contact of 3.24 Å.
2-(4-Acetylthiophenylethynyl)-4-nitro-5-phenyl-ethynyl-aniline (11) 是通过改进的路线合成的,与文献中的方法相比具有许多优点。关键的中间体是 2-乙炔基-4-硝基-5-苯基乙炔基苯胺(6),它是从 2,5-二溴乙酰苯胺(5 个步骤,总收率 68%)中得到的。在 Sonogashira 偶联条件下,6 与 1-乙酰硫基-4-碘苯反应,得到 11(56%)。化合物 11 的特征通过 CHN 分析、质谱分析以及 1H 和 13C NMR 光谱分析得出。2-bromo-4-nitro-5-phenylethynylaniline (4)、2-(3-hydroxy-3-methylbutynyl)-4-nitro-5-phenylethynylaniline (5) 和 2-[(4-methoxybenzylthio)phenylethynyl]-4-nitro-5-phenylethynylaniline (15) 的晶体结构已经确定,11 的化学结构也由此得到证明。分子内接触 O(1)--C(7) 在 4 中为 2.692(2) Å,在 15 中为 2.677(2) Å,比标准范德华 O-C 接触 3.24 Å 短得多。