Ultrasound-enhanced one-pot synthesis of 3-(Het)arylmethyl-4-hydroxycoumarins in water.
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.
Palmisano
Giovanni
G
Dipartimento di Scienze Chimiche e Ambientali, Università dell'Insubria, Como, Italy.
Tibiletti
Francesco
F
Penoni
Andrea
A
Colombo
Francesca
F
Tollari
Stefano
S
Garella
Davide
D
Tagliapietra
Silvia
S
Cravotto
Giancarlo
G
D001557:Benzenesulfonates / Q000737:chemistry; D003374:Coumarins / Q000138:chemical synthesis* / Q000737:chemistry*; D004095:Dihydropyridines / Q000737:chemistry; D013010:Sonication; D013501:Surface-Active Agents / Q000737:chemistry; D014867:Water / Q000737:chemistry*
D001557:Benzenesulfonates; D003374:Coumarins; D004095:Dihydropyridines; D013501:Surface-Active Agents; D014867:Water; C001114:dodecylbenzenesulfonic acid; C038806:1,4-dihydropyridine