Hypervalent Iodine(?)-Mediated Decarb Oxylation Of ?-Keto Acids

The catalytic decarboxylation reaction,which is a bionic synthesis reaction,has been widely studied by organic synthesis chemists,because it has the advantages of being environmentally friendly,mild reaction conditions and high reaction efficiency.Enol esters,?-keto acids and their esters are the main substrates for such reactions.At present,the research of catalytic decarboxylation reaction of ?-keto acid mainly concentrates on the coupling reaction of the enolization as the nucleophile after the decarboxylation reaction with the electrophiles.The reaction catalyst are mostly bifunctional organic nonmetallic catalysts.Metal catalyst,such as Nickel,ytterbium,iridium are also used.Hypervalent Iodine is a potentially substitute for metal catalyst and has similar reactivity with metal catalyst,and has the advantages of being environmentally friendly and mild in reaction compared to metal compounds.At present,Hypervalent Iodine-mediated decarboxylation of ?-keto acids were reported less.We choose iodobenzene diacetic acid,which is widely used chemical reagents.We have carried out a preliminary study on the decarboxylation reaction of ?-keto acid.These results are as follows:(1)The decarboxylation oxidative of ?-keto acid was first achieved,and the optimal conditions for decarboxylation oxidative of ?-ketoacetic acid were obtained by optimizing reaction conditions.Under the optimum conditions,the substrate tolerance of the reaction was investigated.It was found that this reaction can be carried out efficiently,whether it is electron deficient,aryl,aryl,heterocyclic or aliphatic ?-keto acid.At the same time,propionic acid,cyclohexanecarboxylic acid as an acyloxy source,can also be great to achieve the corresponding decarboxylation.Finally,through the validation experiments,the possible reaction mechanism of the reaction was put forward.(2)Using the carbonyl ?-azide as the reaction intermediate,the one-pot decarboxylation and azide reaction of ?-keto acid was realized.The optimum reaction conditions were obtained by optimizing reaction condition.Under the optimum condition,it was found that whichever the functional group were the electron-rich and the electron-deficient,heterocyclic,naphthalene ring,aliphatic or carbonyl ?-methylated ?-keto acids,it can be efficiently reacted with the substrate achieve.Finally,based on the mechanism verification experiment,the possible reaction mechanism of the reaction was put forward.(3)The ?-keto acid was starting material to synthesize acyl azide compounds by a one-pot method.The optimum reaction condition was obtained by the screening of the conditions.Under the optimal condition,the substrate was expanded and it was found that the rich or electron-withdrawing aryl ?-keto acid could be better to convert to the acyl azide compound,and the aliphatic ?-keto acid could not be achieved.Probably the aliphatic acyl azide compounds have too low boiling points.Finally,through some mechanism validation experiments,the reaction mechanism is proposed combined with the known literature...