5-Trifluoromethyl-1,2-dimethyl-1H-pyrazolium chlorides: synthesis and , , and NMR chemical shifts

Synthesis of new 1,1′‐carbonyl‐bis[3‐aryl(heteroaryl)‐5‐(trihalomethyl)‐1H‐pyrazoles] and trifluoromethyl derivatives through ring‐opening reactions

“…According to our previous experience, trifluoromethyl vinyl ketones 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h , 1i readily react with substituted hydrazines to give only 5‐CF 3 substituted pyrazoles [3–9]. In this study, we found that 1,3‐diaminoguanidine monohydrochloride reacted specifically as a bis‐1,2‐dinucleophile with enones 1a , 1b , 1c , 1d , 1e , 1f , 1g , 1h , 1i and 8a , 8b , 8c , 8d , 8e , 8f to give bis‐pyrazoles linked through a carbonyl carbon.…”

“…The structures of 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h , 3i and 9a , 9b , 9c , 9d , 9e , 9f were deduced from their NMR spectra ( 1 H and 13 C) and by comparison with NMR data of other pyrazoles formerly synthesized in our laboratory [5–9].…”

“…The introduction of fluorine(s) into heterocyclic rings is still limited and the trifluoromethyl substituted α,β‐unsaturated ketones represent a practical way to access such compounds [3–11]. In recent years, the synthesis of trifluoromethyl pyrazoles has drawn much attention and the literature has reported a series of specific 5‐CF 3 substituted pyrazoles.…”

“…In recent years, the synthesis of trifluoromethyl pyrazoles has drawn much attention and the literature has reported a series of specific 5‐CF 3 substituted pyrazoles. The main synthetic methods to prepare such compounds involve CCC and NN atom fragments in cyclization reactions of substituted hydrazines or derivatives thereof with 4‐alkoxy‐1,1,1‐trifluoro‐3‐alken‐2‐ones [3–9].…”

The reaction of aryl and heteroarylhydrazines with aryl‐trifluoromethyl β‐diketones

“…Owing to the presence of the trifluoromethyl group, it is possible to isolate the corresponding 5-hydroxy-5-trifluoromethyl-2 -pyrazolines [7][8][9][10] in some cases. Therefore, three kinds of compounds are expected from the reaction between 1 and hydrazines 2-6: 3-trifluoromethyl-5-arylpyrazoles 7-11, 3-aryl-5-hydroxy-5-trifluoromethyl-2 -pyrazolines 12-16 and their dehydration products, 3-aryl-5-trifluoromethylpyrazoles 17-21 (Scheme II).…”