Asymmetric Dearomatization of 1-Aminonaphthalene Derivatives by Gold-Catalyzed Intramolecular Double C–C Bond Formation

Radical-mediated chemo-divergent recyclization of 1,2,3,4-benzothiatriazine-1,1-dioxides: alkyl migration and dearomatization

A divergent denitrogenation/recyclization of 1,2,3,4-benzothiatriazine-1,1-dioxides is disclosed, including C(sp2)-alkyl transposition and aniline dearomatization. Regarding the alkyl migration process, a rare radical-mediated model is presented. Synthetically, sterically-congested biaryl sultams and ortho-all carbon quaternary stereocenter-substituted imines are expeditiously assembled in a simple reaction system. Mechanistic insights indicate that an innovative pattern of diradical-triggered addition probably plays an essential role in the process of C(sp2)-alkyl transformation.

Platinum-Catalyzed Intramolecular Spirocyclization of N-(Methylnaphthalenyl)propiolamides via Formal Aromatic Ene Reaction

It has been established that an in situ-generated cationic platinum(II)/rac-BINAP complex catalyzes the intramolecular dearomative 5-endo spirocyclization of N-(methylnaphthalenyl)propiolamides via the deprotonation-protonation sequence (formal aromatic ene reaction). Mechanistic studies revealed that our previously reported dearomative 6-endo cyclization followed by the Friedel-Crafts reaction is kinetically and thermodynamically unfavored, and thus, the 5-endo spirocyclization proceeds selectively.

Catalytic Dearomative Spirocyclization via Gold Carbene Species Derived from Ynamides: Efficient Synthesis of 2-Azaspiro[4.5]decan-3-ones

An intramolecular catalytic dearomatization of phenols via gold carbene species proceeded to provide 2-azaspiro[4.5]decan-3-ones. The use of NHC ligand and water as a co-solvent was critical for achieving high reactivity. This reaction did not require hazardous diazo compounds as carbene sources and proceeded even under air. The obtained spirocyclic product could be readily transformed into a gabapentin derivative by hydrogenation and deprotection.

Recent advances in enantioselective gold catalysis

Interest in homogeneous gold catalysis has undergone a marked increase. As strong yet air- and moisture-tolerant π-acids, cationic gold(i) complexes have been shown to catalyze diverse transformations of alkenes, alkynes and allenes, opening new opportunities for chemical synthesis. The development of efficient asymmetric variants is required in order to take full advantage of the preparative potential of these transformations. During the last few years, the chemical community has achieved tremendous success in the area. This review highlights the updated progress (2011-2015) in enantioselective gold catalysis. The discussion is classified according to the π-bonds activated by gold(i), in an order of alkynes, allenes and alkenes. Other gold activation modes, such as σ-Lewis acid catalyzed reactions and transformations of diazo compounds are also discussed.

Gold(i) catalyzed cascade cyclization: intramolecular two-fold nucleophilic addition to vinylidenecyclopropanes (VDCPs)

A gold catalyzed cascade cyclization of vinylidenecyclopropanes to give spiro[cyclopenta[a]naphthalene-1,1′-cyclopropanes] in moderate to good yields upon gold catalysis through a two-fold intramolecular nucleophilic addition.

A Gold-Catalyzed Domino Cyclization Enabling Rapid Construction of Diverse Polyheterocyclic Frameworks

We report herein an efficient gold(I)-catalyzed post-Ugi domino dearomatization/ipso-cyclization/Michael sequence that enables access to libraries of diverse (hetero)arene-annulated tricyclic heterocycles. This process affords novel complex polycyclic scaffolds in moderate to good yields from readily available acyclic precursors with excellent chemo-, regio-, and diastereoselectivity. The power of this strategy has been demonstrated by the rapid synthesis of 40 highly functionalized polyheterocycles bearing indole, pyrrole, (benzo)furan, (benzo)thiophene, pyrazole, and electron-rich arene groups in two operational steps.

Gold(I) Catalyzed Dearomative Claisen Rearrangement of Allyl, Allenyl Methyl, and Propargyl Aryl Ethers

Claisen rearrangements of allyl aryl ethers to generate enones bearing all carbon quaternary centers are accelerated by Ph₃PAuNTf₂ under mild conditions in good yields. Multiple C-C bond containing variants of the allyl fragment are viable, including alkylidenecyclopropanes, allenes, and alkynes, which generate all-carbon stereogenic centers substituted with vinyl cyclopropanes, 1,3-butadienyl, and allenyl substituents, respectively, for subsequent synthetic manipulation. With allyl phenyl ethers, the product of the [3,3] rearrangements can be trapped by a tandem [4 + 2] cycloaddition to generate complex molecular scaffolds from readily available, achiral starting materials.

Gold-catalyzed diastereoselective domino dearomatization/ipso-cyclization/aza-Michael sequence: a facile access to diverse fused azaspiro tetracyclic scaffolds

A facile and diversity-oriented access to complex tetracyclic benzo[e]pyrrolo[2,3-c]indole-2,4,7(5H)-triones through a post-Ugi gold(i)-catalyzed domino dearomatization/ipso-cyclization/aza-Michael sequence is elaborated.

Chiral N,N′-dioxide/Sc(OTf)3 complex-catalyzed asymmetric dearomatization of β-naphthols

A highly enantioselective and Z-selective dearomatization of β-naphthols with alkynones has been accomplished using a chiral N,N′-dioxide–Sc(OTf)₃ complex with excellent outcomes.

Construction of spirocarbocycles via gold-catalyzed intramolecular dearomatization of naphthols

A highly efficient, gold-catalyzed intramolecular dearomatization reaction of naphthols via 5-endo-dig cyclization is described. This facile and direct approach furnishes spirocarbocycles in excellent yields under mild conditions.

Catalytic asymmetric dearomatization (CADA) reactions of phenol and aniline derivatives

In this tutorial review, an up to date summary of recent progress in catalytic asymmetric dearomatization (CADA) reactions of phenol and aniline derivatives is presented.

Dearomatization of Indoles via Palladium-Catalyzed Allylic C-H Activation

The first Pd-catalyzed allylic dearomatization of substituted indoles triggered by C-H bond activation is reported. The presence of a catalytic amount of 2,5-DMBQ is proven to be a key factor for the high yield. This one-pot tandem allylic C-H activation/dearomatization sequence provides a straightforward access to 3,3-disubstituted indolines.