Synthesis of 2-Pyrazolines with a CF 3 - and Alkyne-Substituted Quaternary Carbon Center via [3 + 2] Cycloaddition of β-CF 3 -1,3-enynes and Diazoacetates.

Given the importance of both the CF 3 group and the alkyne moiety in synthetic/medicinal chemistry, we report here the first example of efficient synthesis of 2-pyrazolines with a CF 3 - and alkyne-substituted quaternary carbon center. This methodology has the advantages of high functional group compatibility, the avoidance of base and open-flask conditions, easily available and easy to handle reagent, and broad substrate scope. Notably, this protocol allows for the late-stage functionalization of biologically active molecules and the gram-scale synthesis.