Intramolecular Pd(II)-catalyzed cyclization of propargylamides: straightforward synthesis of 5-oxazolecarbaldehydes.
Direct synthesis of 2-substituted 5-oxazolecarbaldehydes was performed by intramolecular reaction of propargylamides through treatment with a catalytic amount of Pd(II) salts in the presence of a stoichiometric amount of reoxidant agent. The heterocyclization process was well-tolerated by a wide range of aryl, heteroaryl, and alkyl propargylamides. This protocol constitutes a valuable synthetic pathway to 5-oxazolecarbaldehydes, alternative to the formylation on oxazole rings, often unsatisfactory in term of regioselectivity and yields.
Beccalli
Egle M
EM
Istituto di Chimica Organica A Marchesini, Facoltà di Farmacia, Università di Milano, Milano, Italy.
Borsini
Elena
E
Broggini
Gianluigi
G
Palmisano
Giovanni
G
Sottocornola
Silvia
S
D000447:Aldehydes / Q000138:chemical synthesis*; D000577:Amides / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D009682:Magnetic Resonance Spectroscopy; D010080:Oxazoles / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
D000447:Aldehydes; D000577:Amides; D010080:Oxazoles; D010165:Palladium