1372806-68-2Relevant articles and documents
Ortho-carboxylate effects in copper-mediated nucleophilic substitution of halothiophenecarboxylic acids and halobenzoic acids with sodium bisulphite
Ramaswamy, Govindarajan K.,Mohanasundaram, Thanigaiarasu,Velayutham, Murugesan,Kuppuswamy, Balasubramanian K.
, p. 884 - 892 (2011)
Ortho-carboxylate effects in Ullmann type nucleophilic substitution reactions were found to be much more pronounced as compared to those of other substituent and steric factors. In this study, we propose an ortho halogen assisted intramolecular oxidative addition-reductive elimination mechanism that fits our experimental observations. Experimental data has been generated with halothiophenecarboxylic acids and halobenzoic acids by performing copper-mediated nucleophilic substitution with scant referred sodium bisulphite as nucleophile under aqueous conditions. The novel mechanism was used to establish a new and improved process for preparation of monopotassium salts of 3-sulphothiophene-2-carboxylic acid, 2-sulphobenzoic acid, and 5-sulphothiophene-2-carboxylic acid. These monopotassium salts are critical intermediates and building blocks in the preparation of several therapeutically valuable drugs. The differences in reactivity between the halogens, chlorine and bromine was utilized to prepare aryl ethers including 2-acetyl-3- phenoxythiophene and 2-acetyl-3-(m-tolyloxy)thiophene that have not been reported in literature so far.
