A Major Advance in the Synthesis of Fluoroalkyl Pyrazoles: Tuneable Regioselectivity and Broad Substitution Patterns.

A novel approach towards highly functionalized fluoroalkyl pyrazoles was developed by using fluoroalkyl amino reagents in combination with a variety of fluorinated ketimines. Tuneable introduction of fluoroalkyl groups in the 3- and 5-positions was possible by using vinamidinium intermediates or the corresponding enamino ketones after hydrolysis. These high-value building blocks can give rise to a large number of analogues for bioactivity screening and discovering new heterocyclic bioactive ingredients in various life science fields.

Liquid-Phase Decarboxylation of Aromatic Haloformates: A New Access to Chloro- and Fluoroaromatics.

The treatment of phenyl chloroformates 1 with a Lewis acid in the liquid phase resulted in decarboxylation to the corresponding chloroaromatics 2. Fluoroaromatic compounds were synthesized from phenylchloroformates 1 through a sequential fluorination/decarboxylation in the liquid phase by treatment with excess anhydrous hydrogen fluoride under mild conditions. In all cases, yields were increased by performing the reaction in 1,2,4-trichlorobenzene, which is inert to Friedel-Crafts reactions.