LiBF4 integrated into [BMIm]BF4: an ionic-liquid metal composite and homogeneous catalyst for efficient synthesis of pyran-annulated heterocycles

• Published in: Applied organometallic chemistry Vol. 28; no. 3; pp. 146 - 150
• Main Authors: Rad-Moghadam, Kurosh, Taghizadeh Valadi, Alireza, Alipour, Arefeh
• Format: Journal Article
• Language: English
• Published: HOBOKEN Blackwell Publishing Ltd 01.03.2014; Wiley
• Subjects: [BMIm]BF4-LiBF4; Chemistry; Chemistry, Applied; Chemistry, Inorganic & Nuclear; isocyanide; metallic ionic liquid; Physical Sciences; pyran derivatives; Science & Technology; three-component reaction; three-component reaction; pyran derivatives; [BMIm]BF4-LiBF4; ISOCYANIDES; metallic ionic liquid; DERIVATIVES; isocyanide
• ISSN: 0268-2605; 1099-0739
• DOI: 10.1002/aoc.3099

The ionic liquid [BMIm]BF4 doped with LiBF4 was found to efficiently catalyze the three‐component reaction between isocyanides, acetylenic esters and enols or phenols at room temperature, leading to rapid synthesis of 2‐aminopyran‐annulated systems in fairly high yields. Efficiency of this catalysis and its benefits in terms of improved yields and reaction times could be ascribed to involvement of relatively stable organolithium intermediates which make the reaction more feasible. The ionic solution tolerates a significant amount of dissolved LiBF4, while remaining fluid at room temperature to serve as solvent for the organic substrates. It retains its initial integrity after use and recovery, as it could be recycled several times without appreciable catalytic decrements. The catalytic activity of the ionic composite is completely lost in the absence of LiBF4. Copyright © 2014 John Wiley & Sons, Ltd. Diverse syntheses of pyran‐annulated compounds via the three‐component reaction between isocyanides, acetylenic esters and phenolic substrates were catalyzed efficiently in the ionic liquid [BMIm]BF4 doped with LiBF4 at room temperature. Formation of organolithium species from stabilizing collapse of the reactive anionic intermediates with the lithium cations of the ionic liquid was postulated as the origin of facility of the syntheses.