Chemoselectivity Profiling in the Alkylation of 2-Chloroethylurea Derivatives with Secondary Amines

The ureido moiety stands as one of the most regarded scaffolds in medicinal and organic synthesis. In this study, we endeavored to synthesize a product containing tertiary amine moieties through the nucleophilic substitution reaction of the 2-chloroethyl urea derivative with a secondary amine, utilizing either inorganic bases, such as K2CO3 or organic bases like triethylamine as acid-binding agents in diverse reaction media. Unfortunately, the reaction failed to yield the desired nucleophilic substitution product in high yield, attributed to the reactivity of the 2-chloroethyl urea derivative. The structures of potential impurities were elucidated based on comprehensive spectroscopic data, including 1H NMR, 13C NMR, HRMS, HMBC, and HSQC.