73 research outputs found
Synthesis of Tetrazole-Derived Organocatalysts via Azido-Ugi Reaction with Cyclic Ketimines
A new route to tetrazole-derived
cyclic amines based on the TMSN<sub>3</sub>-modified Ugi reaction
with 2-substituted cyclic imines was
elaborated. The reaction allows the direct preparation of five-, six-,
and seven-membered cyclic amines substituted with a tetrazole ring,
which are important types of organocatalysts. The scope and limitations
of this method are discussed. In the case of the Ugi reaction with
benzyl isocyanide, the N-substituted tetrazoles can be easily debenzylated
under catalytic hydrogenation conditions to form NH-tetrazoles in
quantitative yields. It was demonstrated that both enantiomers of
tetrazole-derived cyclic amines can be prepared by resolution with
tartaric acid, thereby initiating a simple route to chiral derivatives.
One of the obtained chiral tetrazoles was efficiently used as an organocatalyst
in the amination reaction
Diastereoselective Ugi reaction without chiral amines:the synthesis of chiral pyrroloketopiperazines
Preparation of α,β-Unsaturated Ketones Bearing a Trifluoromethyl Group and Their Application in Organic Synthesis
The approaches to the synthesis of α,β-unsaturated CF3-containing ketones and their use in organic chemistry are reviewed. The synthetic applications of these ketones are discussed. The formation of 4-, 5-, 6- and 7-membered heterocycles bearing a CF3 group based on reactions of α,β-unsaturated CF3-containing ketones with different nucleophiles are discussed
An Efficient Synthesis of 2-CF3-3-Benzylindoles
The reaction of α-CF3-β-(2-nitroaryl) enamines with benzaldehydes afforded effectively α,β-diaryl-CF3-enones having nitro group. Subsequent reduction of nitro group by NH4HCO2-Pd/C system initiated intramolecular cyclization to give 2-CF3-3-benzylindoles. Target products can be prepared in up to quantitative yields. Broad synthetic scope of the reaction was shown. Probable mechanism of indole formation is proposed
Synthesis and Reactions of 3-Halogenated 2-CF<sub>3</sub>-Indoles
Halogenation of 2-trifluoromethylindole afforded 3-chloro-, 3-bromo- and 3-iodo derivatives in up to 98% yield. Methyl-, benzyl- and tosyl-groups can be installed at the nitrogen atom of prepared indoles in high yields by base catalyzed reaction with the corresponding alkylating (sulfonylating) reagents. A high synthetic utility of the prepared haloindoles in the reaction with various nucleophilies was shown. The reaction with 4-methylthiophenol and copper cyanide afforded the corresponding sulfides and nitriles in high yield. Palladium catalyzed cross-coupling with phenyl boronic acid and phenylacetylene gave the corresponding 3-phenyl-2-CF3-indoles and acetylenic derivatives in 72–98% yield
Regioselective Synthesis of New Family of 2-Substituted 1,2,3-Triazoles and Study of Their Fluorescent Properties
Modification of 5-aryl-4-trifluoroacetyltriazoles at the NH-moiety was investigated. Screening of the alkylation conditions revealed that using Na2CO3 as a base and DMF as a solvent of 2-substituted triazoles can be preferentially prepared in up to 86% yield. In the best cases, the amount of minor 1-alkyl isomer was less than 6%. SNAr reaction of the 5-aryl-4-trifluoroacetyltriazoles with aryl halides having electron-withdrawing groups led to regiospecific formation of 2-aryltriazoles isolated in good-to-high yields. Chan–Lam reaction of the 5-aryl-4-trifluoroacetyltriazoles with boronic acids afforded 2-aryltriazoles as single isomers in up to 89% yield. The subsequent reaction of the prepared 2-aryltriazoles with primary and secondary amines gave a set of amides of 4-(2,5-diaryltriazolyl)carboxylic acid. The fluorescent properties of the prepared 2-substituted derivatives of triazoles were investigated to demonstrate their utility as new efficient luminophores having more than 60% quantum yields
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