A convenient 1,3-dipolar cycloaddition–reduction synthetic sequence from 2-allyloxy-5-nitro-salicylaldehyde to aminobenzopyran-annulated heterocycles
作者:Narsidas J. Parmar、Bhavesh R. Pansuriya、Balvantsingh M. Labana、Rajni Kant、Vivek K. Gupta
DOI:10.1039/c3ra42220h
日期:——
A microwave-assisted, one-pot synthesis of some nitro benzopyran-annulated pyrroles as well as pyrrolo-fused isoquinolines via a 1,3-dipolar cycloaddition, which involves the in situ generation of azomethine ylide formed by reacting secondary amines with 2-allyloxy-5-nitro-salicylaldehyde, has been achieved in a solvent-free environment. Compared to methods of conventional and thermal heating, the present microwave-assisted method is rapid and highly efficient. In addition, amino analogous heterocycles were successfully accessed after treating the reaction mass further with iron in acidic medium, which also highlights a one-pot procedure for a new 1,3-dipolar cycloadditionâreduction synthetic sequence. All amino-products are new bioprofiles and anticipated to be effective drug-like candidates. All compounds were characterised based on their elemental analysis, mass, IR, and 1H and 13C NMR spectroscopic data. The stereochemistry of the product was confirmed by 2D NMR COSY and NOESY experiments, which, on the basis of single crystal X-ray diffraction data analysis, was further confirmed and supported.
在无溶剂条件下,通过1,3-偶极环加成反应实现了一种微波辅助的一锅法合成含硝基苯并吡喃并吡咯以及吡咯并合异喹啉类化合物的方法,该反应涉及由二级胺与2-烯丙氧基-5-硝基水杨醛反应原位生成的偶氮甲碱叶立德。与传统和热加热方法相比,当前的微波辅助方法快速且高效。此外,通过在酸性介质中进一步用铁处理反应混合物,成功合成了氨基类似杂环化合物,这也突出了一种新的1,3-偶极环加成-还原合成序列的一锅法程序。所有氨基产物均为新的生物谱,有望成为有效的类药物候选物。所有化合物均根据其元素分析、质谱、红外光谱以及1H和13C核磁共振波谱数据进行表征。产物的立体化学通过2D NMR的COSY和NOESY实验确认,并基于单晶X射线衍射数据分析进一步验证和支持。