Synthesis of Fluoro-Aromatics by Balz-Schiemann Reaction ?A Greener Approach

Abstract

Abstract:A greener approach for the preparation of fluoro-aromatics by diazotization of aromatic amines followed by thermal decomposition of derived tetrafluoroborate in ionic liquids has been developed. The advantages of this procedure are simplicity of reaction, no workup, high purity of the product, safer process, low waste effluents and commercializable processes with recyclability of ionic liquids.

Practical Synthesis of (3aR, 9bR)-8-Fluoro-7-(perfluoropropan-2-yl)-9b-(phenylsulfonyl)-2,3,3a,4,5,9b-hexahydro-1H-benzo[e]indole: An Advanced Intermediate to Access the RORγt Inverse Agonist BMT-362265

“…For example, (i) this synthetic protocol employed 12 linear steps from 6-iodotetralone 1 with an overall yield of only 9.5%; (ii) incorporation of a fluoro moiety via aromatic nitration using the KNO 3 /H 2 SO 4 mixture resulted in significant safety issues, for example, the potential explosive nature of aromatic nitro derivatives . (iii) due to the exothermic nature of the nitration reaction, control on attenuating overnitration could be challenging and (iv) the nitration reaction led to a mixture of regio-isomers, and (v) the potential for uncontrolled thermal decomposition of aryl diazonium fluoroborate salt, especially when carried out on a large scale (vide infra) …”