The synthetic potential of 5-bromo-1,1,1-trifluoro-4-methoxypent-3-en-2-one toward the catalyst-free synthesis of N-pyrrolyl(furanyl)-piperazines, 1,4-diazepanes, and 1,4-diazocanes through a telescoped protocol is reported. This threecomponent one-pot method provided 23 examples with high chemo-and regioselectivity at yields up to 96%.

A study is presented for the synthesis of a series of 1‐tert‐butyl‐3(5)‐(trifluoromethyl)‐1H‐pyrazoles from the reaction of 4‐alkoxy‐1,1,1‐trifluoro‐3‐alken‐2‐ones [CF3C(O)CH=C(R1)(OR), where R = Et and R1 = H or R = Me and R1 = Me, Ph, 4‐Me‐C6H4, 4‐MeO‐C6H4, 4‐F‐C6H4, 4‐Cl‐C6H4, 4‐Br‐C6H4, 4‐I‐C6H4, fur‐2‐yl, thien‐2‐yl, or naphth‐2‐yl] with tert‐butylhydrazine hydrochloride. When [BMIM][BF4] (1‐butyl‐3‐methylimidazolium tetrafluoroborate) and pyridine were used as the reaction media, we obtained a mixture of 1‐tert‐butyl‐3(5)‐trifluoromethylpyrazoles. The formation of 5‐trifluoromethyl‐1‐tert‐butyl‐1H‐pyrazoles with high regioselectivity occurred when the reaction was carried out with NaOH in EtOH. The formation of 1‐tert‐butyl‐3‐trifluoromethyl‐1H‐pyrazoles occurred, after hydrolysis of the 4‐alkoxy‐1,1,1‐trifluoro‐3‐alken‐2‐ones in H2O and H2SO4, followed by cyclization in [BMIM][BF4] and pyridine.

The simple preparation and functionalization of oxa/aza heterocycles requires new and efficient starting materials to be discovered so that regioselective methodologies with a wide range of applications in organic synthesis can be developed. With this in mind, β‐enamino diketones have emerged as a suitable building block for preparing the most diverse (poly)heterocyclic systems, through cyclocondensation or cycloaddition reactions. This review compiles all the reactions that have been conducted using these starting materials, ever since they were first disclosed in 1980.

The use of β-enamino diketones as an easy entry to the regioselective synthesis of [1,2,4]triazolo[1,5-a]pyrimidines is reported. These ketones reacted with 3-amino-1H-1,2,4-triazoles to furnish exclusively 6-substituted 5-(trifluoromethyl)[1,2,4]triazolo[1,5-a]pyrimidines in yields of up to 95%. The regioselectivity of the reactions performed was maintained regardless of the substituent in the starting ketone or aminoazole.

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This study sought to propose the origins of the supramolecular similarity between a series of benzimidazole derivatives structures, and our findings indicated that it occurs due to the approximation of...

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A divergent and regioselective cyclocondensation reaction of β‐enamino diketones with 2‐aminobenzimidazole is reported. The β‐enamino diketones react with 2‐aminobenzimidazole to form exclusively 1,2‐ or 1,4‐regioisomers of benzo[4,5]imidazo[1,2‐a]pyrimidines, depending on the nature of the EWG group in the diketones: when the diketone has a carboxyethyl group, only the 1,2‐regioisomer was obtained; and when the EWG = CF3, only the 1,4‐regioisomer was isolated. The structure of the obtained products was unambiguously determined by 2D‐NMR experiments and single‐crystal X‐ray analysis.