Environmentally benign process for the synthesis of 2,3-disubstituted benzo[b]thiophenes using electrophilic cyclization
作者:Seoyoung Kim、Nikesh Dahal、Tanay Kesharwani
DOI:10.1016/j.tetlet.2013.05.139
日期:2013.8
We have developed a greener process for the synthesis of 2,3-disubstituted benzo[b]thiophenes using electrophilic cyclization as a key step. Our method not only employs an environmentally friendly solvent ethanol, but also utilizes safe and inexpensive inorganic reagents to furnish the desired products in high yields under mild reaction conditions. In addition to iodo- and bromocyclization, chlorocylization was also successfully accomplished. (c) 2013 Elsevier Ltd. All rights reserved.
Green synthesis of benzo[b]thiophenes via iron(III) mediated 5-endo-dig iodocyclization of 2-alkynylthioanisoles
作者:Tanay Kesharwani、Cory T. Kornman、Amanda L. Tonnaer、Andrew D. Royappa
DOI:10.1016/j.tetlet.2015.12.037
日期:2016.1
A reaction of iron(III) chloride with sodium iodide was used to generate iodine for an innovative take on electrophilic cyclization. With ethanol as solvent, the reaction was observed to provide ideal conditions for iodocyclization of 2-alkynylthioanisoles. The fundamental step allows formation of iodine which becomes free to undergo reaction with the starting alkyne to yield the cyclized product. Implementing environmentally benign and simple chemistry, 2-iodosubstituted benzo[b]thiophenes were synthesized in high yields to produce an interesting display of useful molecules. (C) 2015 Elsevier Ltd. All rights reserved.
Sodium halides as the source of electrophilic halogens in green synthesis of 3-halo- and 3, n -dihalobenzo[ b ]thiophenes
A convenient methodology for the synthesis of mono- and di-halogenated benzo[b]thiophenes is described herein, which utilizes copper(II) sulfate pentahydrate and various sodium halides in the presence of substituted 2-alkynylthioanisoles. The proposed method is facile, uses ethanol as a green solvent, and results in uniquely substituted benzo[b]thiophene structures with isolated yields up to 96%. The