Direct Addition of TMS-acetylene to Aldimines Catalyzed by a Simple, Commercially Available Ir(I) Complex

Fischer, Christian; Carreira, Erick M.

doi:10.1021/ol017022q

Cited by 255 publications

(70 citation statements)

References 31 publications

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“…[71][72][73] Interestingly, this was achieved by changing the catalytic system to RuCl 3 /Cu I . [73] The origin of the chemoselectivity is believed to be the inability of the indium(III) center to coordinate and activate the imine in water.…”

Section: Controlling the Fate Of Iminium Electrophilesmentioning

confidence: 99%

Chemoselectivity and the Curious Reactivity Preferences of Functional Groups

2009

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Achieving high levels of chemoselectivity has been the Achilles' heel of chemical synthesis. The excitement generated by the successful realization of chemoselective strategies underscores the painstaking efforts to define a set of conditions conducive to selection among the available reaction pathways. We discuss in this Review various aspects of chemoselectivity that have been addressed in a range of synthetic methods over the past decade. We have focused on the proposed mechanistic basis of the reactions under consideration in an attempt to categorize them and highlight the key concepts that have been emerging on the basis of these studies. Our overview of recent advances in chemoselective processes suggests that significant progress has been made, but a lot of challenges lie ahead.

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Section: Controlling the Fate Of Iminium Electrophilesmentioning

confidence: 99%

Chemoselectivity and the Curious Reactivity Preferences of Functional Groups

2009

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“…When the same reaction was performed at 50 or 100 mmol scales, adduct 4a was isolated in slightly better yields (75 or 80%, respectively, entry 12). Using more CuCl did not significantly improve the yield of adduct 4a (entries [17][18][19][20], but using less catalyst caused the yield to be significantly lower under the same reaction conditions (entries [13][14][15][16]. Other catalysts that have previously been used in A 3 -coupling reactions were also tested using our optimized conditions, but only CuBr (entry 21) performed comparatively well.…”

Section: Resultsmentioning

confidence: 99%

“…It is also applicable to various substrates. This transformation can be catalyzed by a large number of transition-metal salts, including copper, 4 iron, 5 cobalt, 6 nickel, 7 zinc, 8 ruthenium, 9 silver, 10 cadmium, 11 indium, 12 ytterbium, 13 iridium, 14 gold, 15 mercury, 16 bimetallic salt combinations, 17 supported metals, 18 and nanostructured materials. 19 It is interesting to note that, although the use of various amines and aldehydes in this method has been described, the number of alkynes used has been limited.…”

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confidence: 99%

A general A³: coupling reaction based on functionalized alkynes

Wendler¹,

Santos²

2013

Quím. Nova

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Recebido em 15/1/13; aceito em 16/4/13; publicado na web em 17/7/13 A range of hydroxypropargylpiperidones were efficiently obtained by a one-pot three-component coupling reaction of aldehydes, alkynols, and a primary amine equivalent (4-piperidone hydrochloride hydrate) in ethyl acetate using copper(I) chloride as a catalyst. The developed protocol proved to be equally efficient using a range of aliphatic aldehydes, including paraformaldehyde, and using protected and unprotected alkynols.Keywords: hydroxypropargylamine; multicomponent reaction; A 3 -coupling. INTRODUCTIONConnecting organic fragments that have desired functionalities by short and inexpensive synthetic routes is one of the most exciting and challenging tasks for organic chemists, and it requires a high level of creativity and elegance.Recently, multicomponent reactions have been receiving significant attention, because multiple carbon-carbon and carbonheteroatom bonds can be generated in a single step, allowing for the straightforward construction of intricate organic compounds. Recent developments in this area have been very impressive, and procedures involving seven 1 and even eight 2 components have been reported.The three-component coupling of aldehydes, amines, and alkynes (A 3 -coupling) is a very efficient method for forming propargylamines by C-H activation.3 A 3 -coupling is more practical than the other methods available for preparing this class of compounds, because no moisture-sensitive stoichiometric organometallics, such as Grignard or organolithium reagents, are involved. It is also applicable to various substrates. This transformation can be catalyzed by a large number of transition-metal salts, including copper, 4 19 It is interesting to note that, although the use of various amines and aldehydes in this method has been described, the number of alkynes used has been limited. Non-functionalized alkynes, such as phenylacetylene and trimethylsilylacetylene, have been used most frequently, but the A 3 -coupling of alkynols, to prepare functionalized allenols, has recently been described. 20In 2006, Gommermann and Knochel described the use of an A 3 -coupling silylated adduct in the asymmetric synthesis of (S)-(+)-coniine. 21 We know of only a few examples of unprotected alkynols being used in the A 3 -coupling reaction, and all of them, except for ones we have previously reported, 22 have been limited to aromatic aldehydes. 23,24 A general procedure for the preparation of hydroxypropargylamines would be very desirable because these chemicals are direct precursors for alkaloids. The desired carbon skeleton could be achieved in a one-pot process using an A 3 -coupling-type protocol and using the correct functionalities for cyclization to form five-and six-(and higher) ring alkaloid systems.In 2006, Carreira reported using 4-piperidone hydrochloride hydrate as a secondary amine source in an A 3 -coupling reaction. 25The authors demonstrated that using this amine source allowed the A 3 -coupling adducts (tertiary amines) to be easily con...

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“…[4] Copper-catalyzed alkyne additions, disclosed by Li et al, also played a prominent role. [5] There have been a few examples of direct additions of alkynes to C=N electrophiles, in which an Ir, [6] Zr, [7] Ag [8] or Au [9] complex was used as a catalyst instead of a zinc or copper complex. Recently, Bolms group has described the dimethylzinc-mediated addition of terminal alkynes to imines without any ligands, [4l] Pedro et al reported a highly enantioselective zinc/BINOLcatalyzed alkynylation of N-sulfonylaldimines.…”

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confidence: 99%