Green and Sustainable Synthetic Organic Chemistry Laboratory, Department of Chemistry, Yogi Vemana University, Kadapa, 516 005, Andhra Pradesh, India.
Department of Physics, Krishna University Dr. M. R. Appa Row College of PG Studies, Nuzvid, 521 201, Andhra Pradesh, India.
Chemosphere. 2022 Dec;309(Pt 1):136667. doi: 10.1016/j.chemosphere.2022.136667. Epub 2022 Oct 3.
In this paper, an environmentally benign silica-supported perchloric acid (HClO-SiO) catalyzed green FCDR strategy has been developed for the synthesis of (Z)-THIs (6) with high stereospecificity via an intramolecular hydrogen bond (IHB) directed approach, involving the reaction of methyl ketones (1), N-bromosuccinimide (NBS) (2), isatins (4) and thiosemicarbazide (5) in ethanol at reflux temperature for 45-60 min in one-pot. The reaction proceeds through the construction of C-Br (α-bromination), C-S & C-N (heterocyclization), and CN (condensation) bonds in one pot. The absolute structure of the compound (Z)-3-(2-(4-(4-bromophenyl)thiazol-2-yl)hydrazono)indolin-2-one (6e) has been confirmed by single-crystal XRD analysis. Further, the role of IHB on Z-configuration of the synthesized (Z)-THIs is proved by single-crystal XRD and H NMR studies. Wide substrate scope, good functional group tolerance, scalability, improved safety since the method circumvents the use of highly lachrymatric α-bromoketones as starting materials, high product yields (up to 98%), short reaction times, reusable solid Brønsted acid catalyst (HClO-SiO), and products that do not require column chromatography purification are all attractive features of this FCDR strategy. Electrochemical properties of THIs (6) are examined by cyclic voltammetry. The HOMO and LUMO energy level of THIs, 6a, 6c, 6d, 6j, 6o-6v, 6y, and 6aa are comparable with the reported ambipolar materials, and the HOMO levels of other THIs, 6b, 6e-6i, 6n, 6w, 6x, 6z and 6 ab-6ae are similar with the most commonly used hole transporting materials (HTMs).
本文开发了一种环境友好的硅负载高氯酸（HClO-SiO）催化的绿色 FCDR 策略，用于通过分子内氢键（IHB）导向方法合成（Z）-THIs（6），具有高立体特异性，涉及在回流温度下在乙醇中一锅法将甲基酮（1）、N-溴代丁二酰亚胺（NBS）（2）、色酮（4）和缩硫脲（5）反应 45-60 分钟。该反应通过一锅法构建 C-Br（α-溴化）、C-S 和 C-N（杂环化）和 CN（缩合）键进行。通过单晶 XRD 分析确证了化合物（Z）-3-（2-（4-（4-溴苯基）噻唑-2-基）腙基）吲哚啉-2-酮（6e）的绝对结构。此外，通过单晶 XRD 和 1H NMR 研究证明了 IHB 对合成的（Z）-THIs 的 Z-构型的作用。该 FCDR 策略具有广泛的底物范围、良好的官能团耐受性、可扩展性、提高的安全性（因为该方法避免了使用高催泪性的α-溴代酮作为起始原料）、高产物收率（高达 98%）、短反应时间、可重复使用的固体 Brønsted 酸催化剂（HClO-SiO）和不需要柱色谱纯化的产物等优点。通过循环伏安法研究了 THIs（6）的电化学性质。THIs（6a、6c、6d、6j、6o-6v、6y 和 6aa）的 HOMO 和 LUMO 能级与报道的双极材料相当，其他 THIs（6b、6e-6i、6n、6w、6x、6z 和 6ab-6ae）的 HOMO 能级与最常用的空穴传输材料（HTMs）相似。
