Synthesis Of Esters And Ketones Based On Amides By N-Heterocyclic Carbene’S Catalysis

As a versatile organic compound,the amides are widely found in nature.Many proteins and alkaloids contain amines bonds.Carboxylic acid derivatives such as acyl chloride,anhydride and ester can be converted to corresponding amides under certain conditions.The resonance stability and poorer electrophilic property of amide bonds,C-N bonds are difficult to break.Therefore,it is a great challenge for the conversion of amides to esters or other compounds in the field of organic chemistry.In this article,we study the reaction conditions for the conversion of amides to esters and ketones,by optimizing the structure of amides and using metal heterocyclic carbene as catalyst.Finally,we realized the activation of amides under mild conditions.1.We developed a kind of heterocyclic carbene containing hydroxyl groups and discussed its catalytic activity in the esterification of amides.The experimental results show that the nitrogen heterocyclic carbene/Ni（AcO）₂ catalyst exhibits high catalytic activity in the catalytic activation of amide N-C bond at room temperature.The easy-to-obtain alkyl alcohols are used as both reactants and solvents,so that the whole reaction process is simple,convenient and environmentally friendly.This method shows strong universality for all kinds of substrates containing electron-withdrawing and electron-donating functional groups.It is worth mentioning that this method can be used for the direct esterification of amides in air,compared with the precatalytic method of Ni（0）in inert atmosphere reported in the literature.2.Using N-heterocyclic carbene ligand/Pd（AcO）₂ catalyst,the coupling reaction of N,N-bis-Boc amide with organic boron reagent to form aryl ketone was realized,and the reaction conditions were optimized.It was found that the reaction exhibited high catalytic activity in toluene at 40℃with K₂CO₃ and Et₃N.The reaction has good substrate universality and provides an effective method for the construction of C-C bonds.