Lewis Acid-Catalyzed Regioselective Ring-Opening Of Epoxy Homoallylic Alcohols And Epoxy Acrylates

As an important functional group in synthetic chemistry,epoxides are easy to synthesizeand prone to be ring opened by a variety of nucleophiles due to the inherent ring-strain in the molecule.This process provide diverse products with two vicinal stereocenters in one step in a stereospecific pathway,which can be further used as versatile building blocks in organic synthesis.One of the challenges of epoxide ring opening lies in th control of regioselectivity.Great efforts have been devoted towards highly regioseletive epoxides ring opening over the past few decades,and directing-group strategy has been successfully applied in the Lewis-acid catalyzed site-selective ring opening of epoxides.By applying this strategy,it is feasible to perform highly regioselective ring-opening reactions on epoxides bearing substituents with similar steric and electronic effect.Herein,we firstly described a C-3 selective ring opening of epoxy homoallylic alcohols with thiophenols and thiols as the nucleophiles under catalysis of a commercially available boronic acid.Through the directing effect of hydroxyl-group nucleophlic attack on the C-3 position of the epoxide moiety is favored in these reactions.Next,a rare-earth-metal-catalyzed regio-and enantioselective ring opening reaction of 2,3-epoxy esters and amides with amines as the nucleophiles is presented.This method features high regiocontrol,broad substrate scope and mild reaction conditions.The selective nucleophilic attack to the C-3 position is controlled by the directing effect of the carbonyl group of the substrates,which provides a new method for the synthesis of α-hydroxyβ-amino esters and amides.