N-Substitution dependent stereoselectivity switch in palladium catalyzed hydroalkynylation of ynamides: a regio and stereoselective synthesis of ynenamides

Dwivedi, Vikas; Babu, Madala Hari; Kant, Ravi; Reddy, Maddi Sridhar

doi:10.1039/c5cc06251a

Cited by 45 publications

(21 citation statements)

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“…General procedure for synthesis of ynenamines : Ynenamines, 2 and 3 were prepared using a slightly modified literature method . To a solution of alkyne (0.4 mmol) and N‐alkynylindole 1 (0.2 mmol) in 1,4‐dioxane (0.4 mL), Pd(PPh 3 ) 2 Cl 2 (0.02 mmol) and triethylamine (0.625 mmol) were added under an argon atmosphere and the resultant mixture was stirred overnight at 50 °C.…”

Section: Figurementioning

confidence: 99%

Regiodivergent Trifluoromethanesulfonic Acid‐Promoted Cycloisomerizations of Ynenamines to Fused Indoles

et al. 2019

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Section: Figurementioning

confidence: 99%

Regiodivergent Trifluoromethanesulfonic Acid‐Promoted Cycloisomerizations of Ynenamines to Fused Indoles

et al. 2019

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“…[3,4] In contrast, b-(carbonylamino)alkenylmetalsa re obtained by syn-carbopalladation of ynamides by using organopalladiums. [5] How-ever, anti-carbometalation of ynamides remains underdeveloped,a lthough the intramolecular carbometalations of ynamidesh ave been reported (Scheme 1b). [6] We recently reported intermolecular anti-carbometalations of carbon-carbon triple bonds by using silylatedn ucleophiles and metal salts, such as InBr 3 ,G aBr 3 ,A lBr 3 ,B iBr 3 ,a nd ZnBr 2 .…”

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confidence: 99%

“…On the other hand, the use of InCl 3 resultedi nayield of only 66 %( Ta ble 1, entry 3). ZnBr 2 , ZnI 2 ,G aBr 3 ,G aI 3 ,a nd BiBr 3 afforded 3aa in moderate yields ( Table 1, entries [4][5][6][7][8]. Other Lewisa cids, such as CuBr and AlBr 3 were not effective ( Table 1, entries 9a nd 10).…”

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Synthesis of (Z)‐β‐(Carbonylamino)alkenylindium through Regioselective anti‐Carboindation of Ynamides and Its Transformation to Multisubstituted Enamides

Kang

Sakamoto

Nishimoto

et al. 2020

Chemistry A European J

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The regioselective anti-carboindation of ynamides by usingI nBr 3 and silylated nucleophilesw as developed to synthesize (Z)-b-(carbonylamino)alkenylindiums. The X-ray crystallographic analysis of an alkenylindium suggested that the reaction proceeded in an anti-addition fashion.I nc ontrastt or eported syn-carbometalationso f ynamides by using organometallics, ac ooperation of InBr 3 and silylated nucleophiles to ynamides achieveda nantiaddition, whichw as supportedb yD FT calculations. The scope of substrates included variousy namides and silylated nucleophiles, such as silyl ketenea cetals and silyl ketene imines. The transformation of synthesized alkenylindiumsb yi odination,r adicalc oupling, and Pd-catalyzed cross-couplings uccessfully afforded trisubstituted enamines with high regio-and stereoselectivities.Enamides are versatile buildingb locks for valuable nitrogencontaining compounds. [1] Ac ombinationo fc arbometalations of ynamides and transformations of the formed metalated enamides is one of the most reliable synthetic methods for multisubstituted enamides. [2] In this strategy,e stablishmento fr egioand stereoselective carbometalation is necessary for selectively synthesizing ad esired enamide among possiblei somers. Syncarbometalation of ynamides of organometallic compounds has been widely studied (Scheme1a). For example, a-(carbonylamino)alkenylmetals are obtained through the syn-addition of organocoppers, -zincs,a nd -lithiums to ynamides. [3,4] In contrast, b-(carbonylamino)alkenylmetalsa re obtained by syn-carbopalladation of ynamides by using organopalladiums. [5] How-ever, anti-carbometalation of ynamides remains underdeveloped,a lthough the intramolecular carbometalations of ynamidesh ave been reported (Scheme 1b). [6] We recently reported intermolecular anti-carbometalations of carbon-carbon triple bonds by using silylatedn ucleophiles and metal salts, such as InBr 3 ,G aBr 3 ,A lBr 3 ,B iBr 3 ,a nd ZnBr 2 . [7] Therefore, we assumedo ur strategy could achieve anti-carbometalation of ynamides. Here, we report the anti-carbometalation of ynamides by using InBr 3 and silyl ketene acetals to synthesize (Z)-b-(carbonylamino)alkenylindiums(Scheme 1c).First, we surveyed metal halides fort he carbometalation of N-ethynylpyrrolidone (1a)b yu sing the silyl ketene acetal 2a (Table 1). The reactiono fy namide 1a by using InBr 3 and 2a followed by the addition of MeOH exclusively gave the product 3aa in 96 %y ield, where the carbon-carbon bond was formed at the carbon atom adjacent to the nitrogen atom (Table 1, entry 1). This results howed that enamide 3aa was produced by the protonationo fb-(carbonylamino)alkenylindium (detailsa re described below). Notably,r egioisomers obtainedf rom a-(carbonylamino)alkenylindiumsw ere not found despite the existenceo fa na mide moiety,w hich often serves Scheme1.Carbometalation of ynamides. Entry YnamideProduct [b] Entry YnamideP roduct [b] 1 4 2 5 3 6[a] InBr 3 (0.5 mmol), 1 (0.5 mmol), 2a (1.5 mmol), CH 2 Cl 2 (1 mL), I 2 (1.5 mmol), and DMF (1.5 mL).[b] Y...

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“…über eine verwandte Pd-katalysierte Alkinylierung von Inamiden, [14] und im selben Jahr beschrieben Hou und Mitarbeiter eine alkylierende Carboxylierung von Inamiden. [15] Tr otz dieser Fortschritte gibt es zurzeit keine Methode, aalkylierte Enamide direkt aus Inamiden herzustellen.…”

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“…Um die Ausbeute der Reaktion weiter zu ver-bessern, wurden die Dauer der Voraktivierung und die Reaktionsdauer sowie -temperatur untersucht (Nr. [10][11][12][13][14][15]…”

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Regio‐ und stereoselektive Synthese α,β‐disubstituierter Enamide durch Voraktivierung von Inamiden

Baldassari

Torre

et al. 2017

Angewandte Chemie

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Eine neue Strategie der Voraktivierung von Inamiden ermçglicht die Verwendung ansonsten inkompatibler Reagenzien und erlaubt somit die Herstellung a,b-disubstituierter Enamide mit hoher Regio-und Stereoselektivität. Mechanistische Analysen deuten auf die intermediäre Bildung einer Triflat-gebundenen Spezies hin, die als Reservoir für hochreaktive Keteniminiumionen fungiert und so die nachfolgende Addition metallorganischer Reagenzien ermçglicht. Hintergrundinformationen und die Identifikationsnummer (ORCID) eines Autors sind unter: https://doi.org/10.1002/ange.201709128 zu finden.

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N-Substitution dependent stereoselectivity switch in palladium catalyzed hydroalkynylation of ynamides: a regio and stereoselective synthesis of ynenamides

Abstract: A highly general palladium catalysed regioselective hydroalkynylation of ynamides for versatile enamide building blocks with an alkyne tether is achieved with an N-substitution dependent stereoselectivity switch under very mild reaction conditions.

Cited by 45 publications

References 59 publications

Regiodivergent Trifluoromethanesulfonic Acid‐Promoted Cycloisomerizations of Ynenamines to Fused Indoles

Regiodivergent Trifluoromethanesulfonic Acid‐Promoted Cycloisomerizations of Ynenamines to Fused Indoles

Synthesis of (Z)‐β‐(Carbonylamino)alkenylindium through Regioselective anti‐Carboindation of Ynamides and Its Transformation to Multisubstituted Enamides

Regio‐ und stereoselektive Synthese α,β‐disubstituierter Enamide durch Voraktivierung von Inamiden

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