Room-temperature, ligand- and base-free Heck reactions of aryl diazonium salts at low palladium loading: sustainable preparation of substituted stilbene derivatives.
The Pd(OAc)(2)-catalyzed Heck reaction of aryl diazonium salts with 2-arylacrylates led to cis-stilbenes with good to excellent stereoselectivity. The environmentally friendly protocol developed in this work features low palladium loading in technical-grade methanol at room temperature under base-, additive-, and ligand-free conditions. The same protocol applied to simple Heck coupling of aryl diazonium salts with methyl acrylate allows astonishingly low palladium loading, down to 0.005 mol%. The stereoselectivity experimentally observed for the synthesis of cis-stilbenes has been rationalized by DFT calculations. Moreover, the role of methanol in promoting the reaction has been clarified by a computational study.
Felpin
François-Xavier
FX
Université de Bordeaux, CNRS-UMR 5255, Institut des Sciences Moléculaires (ISM), 351, Cours de la Libération, Talence, 33405 France. fx.felpin@ism.u-bordeaux1.fr
Miqueu
Karinne
K
Sotiropoulos
Jean-Marc
JM
Fouquet
Eric
E
Ibarguren
Oier
O
Laudien
Julia
J