The multistep reaction mechanism begins with deprotonation of the alcohol, followed by the oxygen-anion attacking the adjacent trichloromethyl position to form an epoxide.
The oxygen, having become attached to the first carbon of the chain during the epoxide formation, simultaneously displaces a second chlorine atom there to form an acyl chloride.
An additional nucleophilic reactant, such as hydroxide or an alkoxide, then triggers an acyl substitution to produce a carboxylic acid or ester.
The Bargellini reaction involves the same type of dichloroepoxy intermediate, formed by a different method, that reacts with a single structure containing two nucleophilic groups.
It thus gives products such as morpholinones or piperazinones, alpha-amino esters or amides in which the amine is tethered to the acyl substituent group.