Stereoselective One‐Pot Synthesis of 1‐Aminoindanes and 5,6‐Fused Azacycles Using a Gold‐Catalyzed Redox‐Pinacol‐Mannich‐Michael Cascade

Yeom, Hankil; Lee, Youngun; Jeong, Jee–Heon; So, Eunsoo; Hwang, Soojin; Lee, Jieun; Lee, Shim Sung; Shin, Seunghoon

doi:10.1002/ange.200906346

Cited by 63 publications

(21 citation statements)

References 58 publications

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“…The inter- or intramolecular oxidation of alkynes has been described using sulfoxides, 409 pyridine N -oxides, 410 nitrones, 411 nitroso- and nitrobenzenes, 412 as well as epoxides, 413 as the oxidizing agent. These processes have been proposed to proceed via α-oxo gold(I) carbenes 468 , 414 although most likely gold(I) carbenoids 469 are involved by attack of the nucleophile to the highly reactive gold(I) carbene (Scheme 154 ).…”

Section: Oxidative Reactionsmentioning

confidence: 99%

Gold(I)-Catalyzed Activation of Alkynes for the Construction of Molecular Complexity

2015

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Section: Oxidative Reactionsmentioning

confidence: 99%

Gold(I)-Catalyzed Activation of Alkynes for the Construction of Molecular Complexity

2015

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“…In this Account, I will discuss our results based both on intramolecular alkyne oxidation and on intermolecular oxidation, with the latter being the focus. I am, however, obligated to point out here that many other researchers including Liu, 17 − 22 Toste, 23 Shin, 24 , 25 Zhang, 26 − 28 Davies, 29 − 31 Gagosz, 32 Hashmi, 33 , 34 Li, 35 and Liu 36 have also made outstanding contributions in this field, which will not be discussed due to the nature of this Account.…”

Section: Introductionmentioning

confidence: 99%

A Non-Diazo Approach to α-Oxo Gold Carbenes via Gold-Catalyzed Alkyne Oxidation

2014

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For the past dozen years, homogeneous gold catalysis has evolved from a little known topic in organic synthesis to a fully blown research field of significant importance to synthetic practitioners, due to its novel reactivities and reaction modes. Cationic gold(I) complexes are powerful soft Lewis acids that can activate alkynes and allenes toward efficient attack by nucleophiles, leading to the generation of alkenyl gold intermediates. Some of the most versatile aspects of gold catalysis involve the generation of gold carbene intermediates, which occurs through the approach of an electrophile to the distal end of the alkenyl gold moiety, and their diverse transformations thereafter. On the other hand, α-oxo metal carbene/carbenoids are highly versatile intermediates in organic synthesis and can undergo various synthetically challenging yet highly valuable transformations such as C–H insertion, ylide formation, and cyclopropanation reactions. Metal-catalyzed dediazotizations of diazo carbonyl compounds are the principle and most reliable strategy to access them. Unfortunately, the substrates contain a highly energetic diazo moiety and are potentially explosive. Moreover, chemists need to use energetic reagents to prepare them, putting further constrains on operational safety.In this Account, we show that the unique access to the gold carbene species in homogeneous gold catalysis offers an opportunity to generate α-oxo gold carbenes if both nucleophile and electrophile are oxygen. Hence, this approach would enable readily available and safer alkynes to replace hazardous α-diazo carbonyl compounds as precursors in the realm of gold carbene chemistry.For the past several years, we have demonstrated that alkynes can indeed effectively serve as precursors to versatile α-oxo gold carbenes. In our initial study, we showed that a tethered sulfoxide can be a suitable oxidant, which in some cases leads to the formation of α-oxo gold carbene intermediates. The intermolecular approach offers excellent synthetic flexibility because no tethering of the oxidant is required, and its reduced form is not tangled with the product. We were the first research group to develop this strategy, through the use of pyridine/quinolone N-oxides as the external oxidants. In this manner, we can effectively make a C–C triple bond a surrogate of an α-diazo carbonyl moiety in various gold catalyses. With terminal alkynes, we demonstrated that we can efficiently trap exclusively formed terminal carbene centers by internal nucleophiles en route to the formation of cyclic products, including strained oxetan-3-ones and azetidin-3-ones, and by external nucleophiles when a P,N-bidentate ligand is coordinated to gold. With internal alkynes, we generated synthetically useful regioselectivities in the generation of the α-oxo gold carbene moiety, which enables expedient formation of versatile enone products. Other research groups have also applied this strategy en route to versatile synthetic methods. The α-oxo gold carbenes appear to be more electrophilic...

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“…The introduction of the tertiary alcohol moiety enables the construction of new skeletons with quaternary centers by a series of cascade reactions. [20] AuCl 3 was used to successfully catalyze the onepot cyclization of 19 to b-aminodiketones 20 in high yield and moderate to high diastereoselectivity (Scheme 8). Analogous to the 6-exo cyclization of substrates 15 (scheme 7), a gold aoxo carbenoid 21 is generated.…”

Section: Oxygen-atom Transfer From Nitronesmentioning

confidence: 99%

Gold α‐Oxo Carbenoids in Catalysis: Catalytic Oxygen‐Atom Transfer to Alkynes

2011

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An overview of reactive gold α-oxo carbenoid intermediates in the gold-catalyzed functionalization of alkynes is presented. Such intermediates can be generated from inter- and intramolecular oxidation of alkynes by nucleophilic oxygen-atom donor groups, such as amine N-oxides, pyridine N-oxides, nitrones, nitro compounds, sulfoxides, and epoxides. These O-atom transfer processes occur by gold-mediated addition-elimination reactions. In catalytic systems, α-oxo carbenoids can undergo nucleophilic attack by imine, arene, and migrating hydride as well as alkyl groups, leading to cascade reactions and the construction of new skeletons. The facile construction of C-E (E=C, N, S, or O) bonds makes it an attractive step-economic approach to value-added molecules from readily available starting materials. The scope, mechanisms, and reactivity of such α-oxo carbenoid species are discussed. The remarkable diversity of structures accessible is demonstrated with various recent examples.

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Stereoselective One‐Pot Synthesis of 1‐Aminoindanes and 5,6‐Fused Azacycles Using a Gold‐Catalyzed Redox‐Pinacol‐Mannich‐Michael Cascade

Cited by 63 publications

References 58 publications

Gold(I)-Catalyzed Activation of Alkynes for the Construction of Molecular Complexity

Gold(I)-Catalyzed Activation of Alkynes for the Construction of Molecular Complexity

A Non-Diazo Approach to α-Oxo Gold Carbenes via Gold-Catalyzed Alkyne Oxidation

Gold α‐Oxo Carbenoids in Catalysis: Catalytic Oxygen‐Atom Transfer to Alkynes

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