Synthesis of trifluoromethylated [1,4]diazepines from 1,1,1-trifluoroalk-3-yn-2-ones

Acid-Switchable Synthesis of Trifluoromethylated Triazoles and Isoxazoles via Reaction of CF3-Ynones with NaN3: DFT Study of the Reaction Mechanism

A detailed study of the reaction of CF₃-ynones with NaN₃ was performed. It was found that the reaction permits the selective synthesis of either 4-trifluoroacetyltriazoles or 5-CF₃-isoxazoles. The chemoselectivity of the reaction was switchable via acid catalysis. The reaction of CF₃-ynones with NaN₃ in EtOH produced high yields of 4-trifluoroacetyltriazoles. In contrast, the formation of 5-CF₃-isoxazoles was observed under catalysis by acids. This acid-switchable procedure can be performed at sub-gram scale. The possible reaction mechanism was supported by DFT calculations. The synthetic utility of the prepared 4-trifluoroacetyltriazoles was demonstrated.

Recent advances in transition-metal catalyzed directed C–H functionalization with fluorinated building blocks

This review focuses on the advances in transition-metal catalyzed reactions with fluorinated building blocks via directed C–H bond activation for the construction of diverse organic molecules with an insight into the probable mechanistic pathway.

Synthesis of Polysubstituted Trifluoromethylpyridines from Trifluoromethyl-α,β-ynones

A novel and efficient method for synthesis of polysubstituted trifluoromethylpyridine derivatives by the Bohlmann-Rahtz heteroannulation reaction is described, which use trifluoromethyl-α,β-ynones as trifluoromethyl building blocks to react with β-enamino esters or β-enamino ketones in the presence of ZnBr₂ to form the trifluoromethylpyridine derivatives in good yields. The protocol has the advantages of readily available starting materials, mild reaction conditions, and high atom economy.

One-Pot Metal-Free Synthesis of 3-CF3-1,3-Oxazinopyridines by Reaction of Pyridines with CF3CO-Acetylenes

The reaction of pyridines with trifluoroacetylated acetylenes was investigated. It was found that the reaction of various pyridines with two molecules of CF₃CO-acetylenes proceeds under mild metal-free conditions. As a result, efficient stereoselective synthesis of 3-arylethynyl-3-trifluoromethyl-1,3-oxazinopyridines was elaborated. Target heterocycles can be prepared in up to quantitative yields.

Electrophilic halogenation of hydrazones of CF3-ynones. Regioselective synthesis of 4-halo-substituted 3-CF3-pyrazoles

An efficient approach for the synthesis of 4-halo-3-CF3-pyrazoles was elaborated using the cyclization of hydrazones of CF3-ynones induced by electrophilic halogenation. This method can be used for the regioselective synthesis of 3-CF3-pyrazoles substituted at the 4-position with any halogen (I, Br or Cl). The high (up to quantitative) yields, mild conditions and simplicity of the reaction protocol are the advantages of the proposed method. It was demonstrated that cross-coupling with 4-iodo-3-CF3-pyrazoles can be used for the synthesis of a broad family of tetrasubstituted pyrazoles. Moreover, it was found that this method is suitable for the synthesis of 4-substituted derivatives of Celebrex and SC-560.

Unsaturated polyfluoroalkyl ketones in the synthesis of nitrogen-bearing heterocycles

This review focuses on the recent achievements and new developments in the synthesis of polyfluorinated aza-heterocycles based on fluorine-bearing enones and ynones published in the last decade.

Theoretical and experimental (15)N NMR study of enamine-imine tautomerism of 4-trifluoromethyl[b]benzo-1,4-diazepine system

The tautomeric structure of 4-trifluoromethyl[b]benzo-1,4-diazepine system in solution has been evaluated by means of the calculation of (15)N NMR chemical shifts of individual tautomers in comparison with the averaged experimental shifts to show that the enamine-imine equilibrium is entirely shifted toward the imine form. The adequacy of the theoretical level used for the computation of (15)N NMR chemical shifts in this case has been verified based on the benchmark calculations in the series of the push-pull and captodative enamines together with related azomethynes, which demonstrated a good to excellent agreement with experiment.