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 acidbinding 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.