Zinc hydride catalyzed hydroboration of esters

Abstract

The conjugated bis-guanidinate (CBG)-supported zinc hydride {LZnH}₂; L = {(ArHN)(ArN)–CN–C(NAr)(NHAr); Ar = 2,6-Et₂-C₆H₃} (I) is utilized as a catalyst for the hydroboration of esters with pinacolborane (HBpin) under mild reaction conditions. Various aryl and alkyl substrates containing electron-donating, withdrawing, and cyclic groups of esters are effectively converted into alkoxy boronate esters as products upon hydroboration. Furthermore, stoichiometric experiments have been performed to understand the plausible reaction mechanism for the hydroboration of esters. Additionally, complex (I) was used for the hydroboration of carbonate, carboxylic acid, and anhydride substrates to showcase the broad substrate scope.