Enantioselective Construction of Tertiary C–O Bond via Allylic Substitution of Vinylethylene Carbonates with Water and Alcohols

Abstract

An efficient method for the enantioselective construction of tertiary C-O bond via asymmetric allylic substitution of racemic vinylethylene carbonates with water and alcohols has been developed. Under the cooperative catalysis system of an in situ generated chiral palladium complex and boron reagent in mild conditions, the process allowed rapid access to valuable tertiary alcohols and ethers in high yields with complete regioselectivities and high enantioselectivities. This protocol represented the first example of direct enantioselective formation of a tertiary C-O bond with water as an oxygen donor. The synthetic utilities of the process have been demonstrated by the elaboration of the products into key intermediates of biologically relevant agents, and chiral tertiary cyclic ethers could also be provided through the sequential reactions of the allylic etherification and ring-closing metathesis.

Diversity‐Orientated Stereoselective Synthesis through Pd‐Catalyzed Switchable Decarboxylative C−N/C−S Bond Formation in Allylic Surrogates

“…In addition, Zhang et al. disclosed an elegant approach for the Pd‐catalyzed asymmetric allylic substitution of VECs with water or alcohols towards the formation of branched allylic ethers and alcohols featuring chiral tertiary carbon centers …”

Palladium‐Catalyzed Decarboxylative Asymmetric Allylic Alkylation: Development, Mechanistic Understanding and Recent Advances

“…Continuing efforts by Zhang on the IDAAA of zwitterionic π‐allylpalladium intermediates generated from VECs has resulted in a fascinating new hydroxylation/etherification process (Scheme ) . The hydroxylation strategy utilizes water as the nucleophile in the presence of a boron reagent to form tertiary alcohols.…”

Non‐Bonding Interactions Enable the Selective Formation of Branched Products in Palladium‐Catalyzed Allylic Substitution Reactions

“…The regioselectivity of the reaction could be finely tuned through the judicious choice of ligands. Unlike the work by Zhang and co‐workers′, three equivalents of Cs 2 CO 3 were added as the metal cation, thereby leading to the formation of a series of enantioenriched tertiary allylic aryl ethers ( 64 ) in good yields and appreciable enantioselectivities through metal‐tethered nucleophilic attack ( 65 ).…”

“…In 2017, the Zhang group developed a palladium‐catalyzed decarboxylative asymmetric allylic substitution reaction of racemic vinylethylene carbonates with water and alcohols, through which chiral tertiary C−O bonds were constructed in a highly efficient and enantioselective manner (Scheme ) . Very interesting, a synergistic catalysis system that consisted of a chiral palladium catalyst and boronic acid was key to this success in terms of both the regio‐ and enantioselectivity.…”