The reaction of α-CF3-β-(2-nitroaryl)enamines with benzaldehydes led to nitro-substituted α,β-diaryl-CF 3 -enones in high yield. Subsequent reduction of the nitro-group to the amino moiety by the Pd/C-NH 4 HCO 2 system resulted in intramolecular cyclization to form a 5-membered hemiaminal which is stabilized by the presence of a CF 3 -group. The reaction of this hemiaminal with various nucleophiles afforded functionalized 2-CF 3 -indoles isolated in up to quantitative yields. High efficiency and broad synthetic scope of all steps of the sequence were demonstrated. A possible mechanism of the reaction is discussed.
An efficient pathway toward a novel
class of trifluoromethyl building
blocks was elaborated. The reaction of α-CF3-enamines
with arylaldehydes resulted in direct synthesis of α,β-diaryl-CF3-enones isolated in up to 93% yield as E-isomers.
The possible reaction mechanism was proposed using the Zimmerman–Traxler
model. The reaction of α,β-diaryl-CF3-enones
with hydrazines opens a novel pathway to trifluoromethylated pyrazolines.
Oxidation of pyrazolines with DDQ opened access to totally regioselective
preparation of 3-CF3-pyrazoles isolated in high yield.
Using this strategy, 4-arylated derivatives of known drugs Celebrex,
Mavacoxib, and SC-560 can be synthesized.
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.
α-CF3-enamines can be prepared by the reaction of pyrrolidine with the corresponding haloalkenes. The prepared enamines react with 2-nitrobenzaldehydes to give highly stereoselectively ortho-nitro-substituted α,β-diaryl-CF3-enones in up to 88% yield....
A novel approach to terminal acetylenes based on catalytic olefination reaction COR of arylaldehydes to form dichloroalkenes followed by treatment with nBuLi was elaborated. This method is atom economical and displays high yields and effectivity. The corresponding alkynes can be prepared in up to 97 % yield. One pot procedure towards CF3‐ynones was elaborated to provide these products in up to 87 % yield starting from dichloroalkenes.
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