Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1265631 | Ultrasonics Sonochemistry | 2011 | 9 Pages |
Abstract
3-(Aryl)methyl-4-hydroxycoumarins were produced in good to excellent yields by reaction between 4-hydroxycoumarin and (hetero)aromatic aldehydes in the presence of Hantzsch 1,4-dihydropyridine (HEH) which works as an hydride donor (i.e., in a sequential Knoevenagel–reductive Michael addition). The sonochemical-assisted procedure (method B) provides an improved and accelerated conversion when compared to conventional silent reactions (method A). Experiments carried out according to method B showed that the reaction could be more efficiently run in the absence of organic solvents, at 30–40 °C in open vessel, without the need of an excess HEH and with simplified work-up and separation procedures.
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Authors
Giovanni Palmisano, Francesco Tibiletti, Andrea Penoni, Francesca Colombo, Stefano Tollari, Davide Garella, Silvia Tagliapietra, Giancarlo Cravotto,