Oxidation Of Acrylamides Mediated By Hypervalent Iodine Reagents

Oxazolones and their derivatives are one of the important five-membered heterocyclic compounds,which show biological and pharmacological activity.Oxazolones derivatives were used as promising intermediates in the synthesis of pharmaceutical and functional materials.Such synthetic utility and pharmacological applications of oxazolones have inspired organic chemists to develop various efficient and elegant protocols for their synthesis.Several nonmetal-and metal-oxidative cyclization studies on the synthesis of oxazolones have been described.However,compared with metal oxidants,nonmetal oxidants are a class of green and environmentally friendly reagents and they have increasingly important application value in synthetic chemistry.Hypervalent iodine reagents have recently received significant attention in synthesis as an oxidant by virtue of their low toxicity,controllable reactivity,ready availability,high stability,easy handling,etc.,especially iodine(?)reagents have been widely applied to the construction of various heterocyclic skeletons.Hypervalent iodine regents,especially iodine(?)reagents mediated oxidative cyclization,rearrangement reactions and cascade reactions etc.have been widely used in the synthesis of various heterocyclic compounds.?-Acyl-?-amino acrylamides are a class of important precursors with multiple nucleophilic and electrophilic sites.They have the structural characteristics of enaminone,1,3-dicarbonyl compound and amide.The different nucleophilic or electrophilic activity of such precursors might provide the feasibility to construct the skeletons of varied heterocycles under different reaction conditions.We studied the oxidative cyclization reaction of ?-acyl-?-amino acrylamides mediated by hypervalent iodine reagents,investigated the mechanism involved in the reactions.We have developed here a novel and efficient synthesis of 3,4,5-trisubstituted oxazol-2(3H)-ones by PhI(OOCCF3)2-mediated oxidation of ?-acyl-?-amino acrylamides.