Re₂O₇/HReO₄ Mediated Intramolecular Hydroacyloxylation of Unactivated Alkenes: A Dual Hydrogen-Bonding Effect

Abstract

This publication describes the application of Re2O7 in hexafluoroisopropanol (HFIP) for the activation of inert as well as electronically deactivated olefins to facilitate a challenging intramolecular hydroacyloxylation reaction. Both HFIP and an internal carboxy group have been proven to be crucial for the successful implementation of this transformation; these are proposed to assist the formation and stabilization of the key cationic intermediate via hydrogen-bonding interactions with perrhenate anion (ReO4 –).

Allure of HFIP in Unsaturated Carbon−Carbon Bond Functionalization

“…The interaction among HFIP solvent, carboxyl functionality, and Re‐catalyst has been identified as indispensable factors for this transformation, facilitating the formation and stabilization of the key cationic intermediate through hydrogen‐bonding interactions with the perrhenate anion (ReO 4 − ) (Scheme 4). [8] …”

“…The interaction among HFIP solvent, carboxyl functionality, and Re-catalyst has been identified as indispensable factors for this transformation, facilitating the formation and stabilization of the key cationic intermediate through hydrogenbonding interactions with the perrhenate anion (ReO 4 À ) (Scheme 4). [8] The potent application of HFIP in combined acid catalysis was further examined by Leboeuf et al of highly deactivating styrene (Scheme 5). [9] This protocol showcased the functionalization of an array of highly deactivating styrene to synthesize a large variety of diaryl alkanes in good to excellent yields.…”

Synthesis of 1-Aryltetralins via Re2O7/HReO4 Mediated Intramolecular Hydroarylations

“…However, most preceding examples only worked for electronically activated alkenes and often required the application of an elevated reaction temperature. Recently, as part of our continuing efforts to use Re 2 O 7 in fluorinated solvents to generate and stabilize electronically challenging carbocations for Friedel–Crafts type alkylations, we realized the activation of highly inert olefins for intermolecular hydroarylations (Figure B) and intramolecular hydroacyloxylations . In this work, we further extend the activation mode to facilitate intramolecular hydroarylation reactions for the facile preparations of biologically relevant 1-aryltetralins (Figure C).…”