An unexpected tetracyclic product isolated during the synthesis of biscoumarins catalyzed by [MIM(CH2)(4)SO3H][HSO4]: Characterization and X-ray crystal structure of 7-(2-hydroxy-4-oxo-4H-chromen-3-yl)-6H,7H-chromeno[4,3-b]chromen-6-one

作者：Tavakoli Hoseini Niloofar^*; Heravi Majid M; Bamoharram Fatemeh F; Davoodnia Abolghasem; Ghassemzadeh Mitra

来源：Journal of Molecular Liquids, 2011, 163(3): 122-127.

DOI：10.1016/j.molliq.2011.08.007

• Biscoumarins
• 4-Hydroxycoumarin
• Ionic liquid
• Unexpected product

Under solvent-free conditions and in the presence of 3-methyl-1-(4-sulfonic acid)butylimidazolium hydrogen sulfate [MIM(CH2)(4)SO3H][HSO4], a Bronsted acidic ionic liquid, the reaction of aromatic aldehydes with 4-hydroxycoumarin has been investigated. A wide range of aromatic aldehydes easily undergoes condensation with 4-hydroxycoumarin to afford biscoumarins with good purity in excellent yields. However, reaction of 2-hydroxybenzaldehyde with 4-hydroxycoumarin gave, not the corresponding biscoumarin, but a tetracyclic compound, 7-(2-hydroxy-4-oxo-4H-chromen-3-yl)-6H,7H-chromeno[4,3-b]chromen-6-one, in high yield.

• 出版日期2011-10-15