Efficient and Scalable Method for the Selective Alkylation and Acylation of Secondary Amines in the Presence of Primary Amines

Selective substitution of secondary amines in the presence of primary amines is performed by using the reaction solvent, methyl isobutylketone (MIBK), as a temporary protecting group for the primary amine. After acylation or alkylation of the secondary amine, the resulting imine intermediate is smoothly hydrolysed, leading to the free primary amine in high yield and purity. This procedure represents a cheap and scalable alternative to multistep methods requiring several protections and deprotections.