Hypervalent iodine oxidation of N-acylhydrazones and N-phenylsemicarbazone: an efficient method for the synthesis of derivatives of 1,3,4-oxadiazoles and .DELTA.3-1,3,4-oxadiazolines
摘要:
The oxidation of ketone N-acylhydrazones 1 by phenyliodine(III) diacetate (PIDA) in alcohol gave 2-alkoxy-DELTA3-1,3,4-oxadiazolines 4 in excellent yields, while the oxidative cyclization of aldehyde N-acylhydrazone 2 by PIDA in methanolic sodium acetate gave 2,5-disubstituted 1,3,4-oxadiazoles in good yields. The oxidation of acetone 4-phenylsemicarbazone afforded 2-(N-phenylimino)-DELTA3-1,3,4-oxadiazoline in excellent yield.