The problem with the reduction of a ketone function in a ketoacid lies with the fact that the reducing reagent, e.g. a Grignard reagent, would not only attack the keto group but also would attack the carboxylic acid. To solve this problem one reacts the carboxylic acid with a beta-amino alcohol which leads to the conversion of the carboxylic acid into an oxazoline. Oxazolines are not attacked by nucleophiles and will therefore remain unaffected by Grignard reagents. The oxazoline later on can be treated with dilute acid to regenerate the carboxylic acid.