Studies On Palladium And Nickel Catalyzed Reduction Of Ethers And Esters With Sodium Formate

Esters and ethers are cheap and readily available chemicals which usrally are less toxic than organic halides.Like organic halides,those compounds can be used used as electrophiles to construct carbon-carbon bonds and carbon-heteroatom bonds.It is well-known that phenolic group and carboxylic groups can be used as a directing group,guiding the functionalzation of the para or ortho-position of a benzene ring.Recently,many transition metal-catalyzed functionalization of C-H bonds directed by esters and ethers were developed.Therefore,if these ester and ether groups can be selectively reduced,we can prepare aromatic compounds from simple phenols in two steps(introduction of groups directed by esters or ethers and subsequent hydrogenation of the C-0 groups).This paper focuses on the selective hydrogenation of ether and ester compounds catalyzed by transition metals.Specific research content and results are as follows:(1)A Ni-catalyzed hydrogenation of C-O compounds with sodium formate is developed.Various esters,i.e.aryl,alkenyl,benzyl pivalates,and even the aryl ethers,were efficiently reduced with a loading of nickel catalysts down to 0.5 mol%.Reactive functional groups such as C-C double bonds,carbonyl,CN,MeS and halogen groups are tolerable.This reaction can be used for the modification of complex molecules and carried out at a large scale?(2)A palladium-catalyzed hydrogenation of ester with sodium formate is developed.This reaction employed Pd(OAc)2 as a catalyst and dcype as a ligand.Both aryl formates and acetates can be converted to the corresponding hydrogenating products under the reaction conditions.This reaction is applicable to the modification of complex molecules,showing potential application in organic synthesis.