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. |