Numerous methods have been developed for the preparation of 2-substituted oxazolines from carboxylic acids using high temperatures of up to 200–220°C, 4 repeated use of SOCl 2 , 5 phosphines together with harmful halogenated hydrocarbons such as CCl 4 or hexachloroethane, 2 or under other drastic reaction conditions. Some other methods using carboxylic esters, 6., and nitriles 7 or aldehydes 8 as starting materials have also been described but most of them utilize ...
