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%.
Chemical investigation of the aerial parts of Leonurus sibiricus L. used in Brazilian folk medicine led to the identification of the following constituents: the labdane-type diterpenoid leojaponin, the phytosterols β-sitosterol and β-sitosterol glucoside and the alkaloid leonurine. The crude extracts obtained from methanol and methanol/1% HCl and pure compounds isolated from L. sibirius were investigated as acetylcholinesterase (AChE) and prolyl oligopeptidase (POP) inhibitors. Extracts obtained by maceration were active against POP (53-58%), but showed weak activity against AChE. The isolated leojaponin and leonurine were evaluated as POP inhibitors.
In this work, the reactivity of 5-bromo-1,1,1-trifluoro-4-methoxypent-3-en-2-one toward primary aliphatic amines was studied. The reaction was found to be extremely selective to synthesize a series of 1-alkyl-4-aminoalkyl-2-trifluoromethyl-1H-pyrroles (13 examples, at yields up to 90%) and a series of highly functionalized β-enaminones (6 examples, at yields up to 78%), with only the amount of amine and the reaction condition needing to be controlled. The structure of the products was unambiguously determined by single crystal X-ray diffraction and 2D NMR experiments.
The N‐functionalization of 4‐amino‐2‐trifluoromethyl‐1H‐pyrroles using alkyl halides is reported. The selectivity of the alkylation reaction was highly dependent on the nature of the alkyl halide and the reaction conditions applied, that is, methyl iodide may furnish N‐methyl or N,N‐dimethyl pyrroles, while allyl bromide furnishes N‐allyl or N,C‐diallyl analogs and propargyl bromide furnishes exclusively N‐propargyl pyrroles. The alkylated products were obtained between 65%–90% yields and were subjected to CuAAC reactions, which furnished conjugated 1,2,3‐triazoles in good yields (72%–91%). The structures of the obtained compounds were unambiguously determined via 2D‐NMR experiments.
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