Recent Progress on Gold-catalyzed Dearomatization Reactions

Abstract

Homogeneous gold catalysis has experienced rapid development since 2004 and generally exhibited high efficiency and good functional group tolerance. On the other hand, catalytic dearomatization reactions provide a unique and straight approach to the construction of highly functionalized molecules with diverse three-dimensional structures from simple aromatic compounds. In this perspective, recent examples on gold-catalyzed dearomatization reactions are summarized in two main categories: gold-catalyzed rearrangements and gold-catalyzed hydrofunctionalizations of alkynes and allenes. In the first category, intra-and inter-molecular dearomatization reactions were achieved via gold-catalyzed rearrangements of propargylic ester and its derivatives. Although this area is still at its early stage, several outstanding asymmetric examples have been reported by Shi and Toste. In the second category, an array of dearomatization reactions via gold-catalyzed hydrofunctionalizations of alkynes and allenes were presented. All these cases have shown great potentials for convenient and straightforward construction of spiro and/or bridged polycyclic molecules, and some of them have exhibited excellent enantioselectivity. In addition, salient features and proposed mechanisms for these two types of reactions are also described.

Organocatalyzed asymmetric dearomative 1,3‐dipolar cycloaddition of 2‐nitrobenzofurans and N‐2,2,2‐trifluoroethylisatin ketimines

“…Catalytic asymmetric dearomatization (CADA) reaction represents a powerful strategy for the synthesis of elaborated chiral complex compounds from readily available planar aromatic substrates 1–10 . In this research area, compared with the well studied on the electron‐rich heteroarenes, such as indoles, pyrroles, quinolones, and isoquinolines, 11–20 the CADA reaction regarding to the electron‐deficient heteroarenes remains relatively underdeveloped.…”

Co(III)/Zn(II)-catalyzed dearomatization of indoles and coupling with carbenes from ene-yne ketones via intramolecular cyclopropanation

“…A hexacyclic ring system that includes a unique cyclopropyl ring fused to an indoline accompanied by three quaternary carbon stereocenters such as lundurines are attractive targets. Traditional methods to construct cyclopropane-fused indoline derivatives include transition-metal-mediated reactions [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36], the classic Simmons-Smith reaction and so on [34][35][36][37][38][39][40][41]. However, highly efficient, environmentally friendly, and atom-economic methods for generating available carbenoids precursors in a catalytic fashion continue to be highly limited [42].…”

Enantioselective Hydrative para‐Dearomatization of Sulfonanilides by an Indanol‐based Chiral Organoiodine Catalyst

“…[3] In the early studies, organoiodine(III) reagents such as (diacetoxyiodo)benzene and [bis(trifluoroacetoxy)iodo] benzene were often used as a stochiometric oxidant to provide valuable functionalized six-membered rings. [4,5] In the last decade, the emergence of chiral organoiodine(I/ III) catalysis has opened up a new opportunity in the oxidative dearomatization, [1c,6-9] although the successful examples are mostly limited to intramolecular ortho dearomatizations. [10][11][12][13][14] Oxidative intermolecular para dearomatization of arenols [15,16] has been regarded as a formidable challenge due to the difficulty of constructing an effective chiral environment at the remote para-position by the conventional chiral organoiodine catalysts.…”