Switchable Multicomponent Cyclization Reactions to Access Fluoroalkylated Dihydropyrimidines and Pyrimidines Under Sol-vent-Free Conditions

The development of switchable solvent-free multicomponent reactions to build high-value-added products is an important demand for organic synthesis. Herein, we detailed the successful implementation of a switchable strategy for the construction of diverse 4-fluoroalkyl-1,4-dihydropyrimidines and 4-fluoroalkyl-pyrimidines via a solvent/additive-free [3 + 2 + 1] annulation, starting from readily available enamines, trifluoroacetaldehyde hydrate or 1-ethoxy-2,2-difluoroethanol and amidines hydrochloride. This reaction conforms to the concept of green synthesis, and provides a new avenue to access valuable fluorinated heterocycles.