The first stage of the process is the
reduction of the carbonyl to give a 1,1,1-trichloro-2-hydroxy structure. The original protocol used
catecholborane with a small amount of one enantiomer of
CBS catalyst (a
Corey–Itsuno reduction). The choice of chirality of the catalyst thus gives selectivity for one or the other stereochemistry of the alcohol, which subsequently controls the stereochemistry of the amino substituent in the ultimate product. This 2-hydroxy structure then undergoes a
Jocic–Reeve reaction using
azide as the
nucleophile. 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 azide then opens this ring by an
SN2 reaction to give a 2-azido structure whose stereochemistry is inverted compared to the original 2-hydroxy. 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. Various other nucleophiles can be used to generate other acyl functional groups. This sequence of steps gives a 2-azido compound, which is then reduced to the 2-amino compound in a separate reaction, typically a
Staudinger reaction. ==Bargellini reaction==