Oxazolidine Formation, or Loss of Acid, from Attempted Fluorination of Amide Side‐Chain in 2‐Nitroimidazoles

Abstract

Reaction of Etanidazole (a 2‐nitroimidazole derivative with an amide side‐chain containing a hydroxyethyl group) with triflic anhydride gives, depending on conditions, a trifluoromethyl(sulfonyl)oxazolidine via a cyclization reaction, or a fluorine‐free formate derivative; reaction with tosyl chloride gives only a chloroethyl derivative. An attempt to replace a Br‐atom in a related propyl‐containing amide side‐chain by a F‐atom forms instead a propylene derivative via loss of HBr. The studies stem from interest in use of 2‐nitroimidazoles with fluorine‐containing amide side‐chains as hypoxia markers.