Oxidative Cyclization of β-Aminoacrylamides Mediated by PhIO: Chemoselective Synthesis of Isoxazoles and 2H-Azirines
摘要:
Cyclization of a variety of beta-aminoacrylamides in the presence of iodosobenzene (PhIO) is described. This process features mild reaction conditions, simple execution, and high chemoselectivity and thereby provides an efficient protocol for the divergent synthesis of substituted isoxazoles and 2H-azirines via switchable N-O and N-C bond formation controlled by simply varying the beta-substituent R-3 of the readily available substrates.
A facile and efficient one-potsynthesis of polysubstituted pyridin-2(1H)-ones from readily available enaminones and the cyanomethyl sulfonium bromide salt in the presence of cesium carbonate is developed, and a mechanism involving sequential nucleophilic vinylic substitution (S(N)V), intramolecular nucleophilic cyclization and dealkylation reactions is proposed.