No abstract

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.

New CCl3‐ and CF3‐substituted enones, bearing additional hidden hydroxymethyl functions, were prepared by acylation of 4‐methylene 1,3‐dioxolanes. The synthesized enones are interesting building blocks for agrochemical and medicinal chemistry research. The reactivity of synthesized enones with various amines was studied, and enaminones 13 and 14 were obtained under NH3 interaction; the reaction with aliphatic primary amines afforded enaminones 17 in high yields as equilibrium mixtures of E and Z isomers. The reaction of fluorinated enone 9c with anilines afforded a mixture of products, including non‐aromatic heterocyclic compounds 25 and 26 bearing the CF3 group as well as furan 27 with CF3 and amino functions at positions 5 and 3, respectively. The hydrolysis of enone 9c afforded cyclic compound 11.

The synthesis of 3,5-bis(fluoroalkyl)-pyrazoles as novel agrophores is described. Commercially available fluoroacetoacetates are treated with BF 3 -activated TFEDMA affording in a straightforward one-pot sequence pyrazole carboxylates in good yields and with excellent regioselectivity. The carboxylate intermediates have been converted into the corresponding pyrazolic acids and submitted to decarboxylation, affording valuable building blocks for the design of novel bioactive ingredients. The found process is suitable for scale up and preparation of compounds in kilogram quantity.

Herein we describe the first practical method for the regioselective preparation of 3,5‐bis(fluoroalkyl)pyrazoles. Starting from commercially available fluoroacetoacetates and by using (tetrafluoroethyl)dimethylamine as a convenient CF2H transfer reagent, this straightforward one‐pot sequence affords highly substituted pyrazoles in good yields and excellent regioselectivity. Furthermore, these carboxylate intermediates were converted into the corresponding pyrazolic acids, which are valuable building blocks for the design of novel bioactive ingredients.