Nickel-Catalyzed Decarbonylative Borylation And Silylation Of Esters

Esters are widely found in a broad range of organic molecules,including pharmaceuticals,agrochemicals,and organic materials,and their selective functionalization represents a challenge in the field of organometallic chemistry.The nickel-catalyzed direct borylation and silylation of phenolic esters has been established and the results are summarized below.(1)We developed a nickel-catalyzed decarbonylative borylation reaction of esters with 5,5,5’,5’-tetramethyl-2,2’-bi(1,3,2-dioxaborinane)(B2znep2),which forms aryl borates in one step.The key to this highly efficient acyl C-O bond borylative cleavage depends on the appropriate choice of ligands and additives in the presence of nickel catalyst.This transformation exhibits good functional group compatibility and can serve as powerful synthetic tools for late-stage functionalization of complex compounds.Two important organonickel(Ⅱ)complexes were successfully separated and characterized by X-Ray,which verified the mechanism of the reaction.(2)We developed a nickel/copper co-catalyzed decarbonylative silylation reaction of esters with silylborane reagent(Bpin-SiEt3),which generated aryl silane very effectively in one step.Copper is essential in this process and active the silylborane to form the Cu-SiEt3 species.This transformation exhibits good functional group compatibility,and can afford the corresponding products including heterocyles in moderate to excellent yields.Based on the mechanism of the borylation of esters,the mechanism of the silylation of ester was similarly speculated.