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A Mechanistic Investigation of the Gold(III)-Catalyzed Hydrofurylation of C–C Multiple Bonds
journal contribution
posted on 2016-10-17, 00:00 authored by Amin Hossein Bagi, Yousef Khaledi, Hossein Ghari, Sebastian Arndt, A. Stephen K. Hashmi, Brian F. Yates, Alireza AriafardThe gold-catalyzed
direct functionalization of aromatic C–H
bonds has attracted interest for constructing organic compounds which
have application in pharmaceuticals, agrochemicals, and other important
fields. In the literature, two major mechanisms have been proposed
for these catalytic reactions: inner-sphere syn-addition
and outer-sphere anti-addition (Friedel–Crafts-type
mechanism). In this article, the AuCl3-catalyzed hydrofurylation
of allenyl ketone, vinyl ketone, ketone, and alcohol substrates is
investigated with the aid of density functional theory calculations,
and it is found that the corresponding functionalizations are best
rationalized in terms of a novel mechanism called “concerted
electrophilic ipso-substitution” (CEIS) in which the gold(III)-furyl
σ-bond produced by furan auration acts as a nucleophile and
attacks the protonated substrate via an outer-sphere mechanism. This
unprecedented mechanism needs to be considered as an alternative plausible
pathway for gold(III)-catalyzed arene functionalization reactions
in future studies.