Regio- and stereoselectivity in palladium-catalyzed cycloreductions of 1,6-enynes in the presence of formic acid or triethylsilane

Oh, Chang Ho; Jung, Hwanyup; Sung, Hye Rhyan; Kim, Jung Duk

doi:10.1016/s0040-4020(01)00008-4

Cited by 25 publications

(5 citation statements)

References 28 publications

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“…Oh also reported the palladium-catalyzed cycloreductions of 1,6-enynes in the presence of formic acid or triethylsilane via an alkylpalladium intermediate and its application in synthesis. 123,124 Iterative trapping of the alkylpalladium species with tethered olefins can be also possible and allows tandem cycloisomerizations. Thus, depending upon the juxtaposition of the unsaturations, Trost achieved highly atom economical syntheses of triquinanes, propellanes, and polyspiranes (eqs 74 and 75).…”

Section: Vinylmetal Pathway/hydrometalation: Palladium Catalystsmentioning

confidence: 99%

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The Behavior of 1,n-Enynes in the Presence of Transition Metals

2002

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Section: Vinylmetal Pathway/hydrometalation: Palladium Catalystsmentioning

confidence: 99%

“…Up to now, few examples of such a sequence of reactions have been described. Oh also reported the palladium-catalyzed cycloreductions of 1,6-enynes in the presence of formic acid or triethylsilane via an alkylpalladium intermediate and its application in synthesis. , …”

Section: 1 Vinylmetal Pathway/hydrometalation411 Vinylmetal Pathway/h...mentioning

confidence: 99%

The Behavior of 1,n-Enynes in the Presence of Transition Metals

2002

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“…[1] Moreover, Michael reaction adducts of the 1,2-diazabuta-1,3-diene system may act as nitrogen ligands [2] for transition metal catalysts, which leads to unusual reaction pathways. [5] The classes of reaction that involve the metalcatalyzed functionalization of enynes include cycloisomerization, [6] reductive cyclization, [7] bismetallative cyclization, [8] carbonylative cyclizations, [9] and dimerization/cyclization. [4] A variety of metal-catalyzed reactions of enynes, which involve a broad range of early and late transition metals, are of interest in the synthesis of functionalized carbo/heterocycles.…”

mentioning

confidence: 99%

“…[3] In common with other Michael additions, 1,2-diazabuta-1,3dienes undergo divergent copper-promoted annulation reactions to form functionalized imidazolines/imidazoles under regiocontrol, whereas the base-promoted cyclization provides both 1-substituted and 1-unsubstituted 4-aminocarbonyl-1Hpyrazol-5(2H)-ones. [5] The classes of reaction that involve the metalcatalyzed functionalization of enynes include cycloisomerization, [6] reductive cyclization, [7] bismetallative cyclization, [8] carbonylative cyclizations, [9] and dimerization/cyclization. [5] The classes of reaction that involve the metalcatalyzed functionalization of enynes include cycloisomerization, [6] reductive cyclization, [7] bismetallative cyclization, [8] carbonylative cyclizations, [9] and dimerization/cyclization.…”

mentioning

confidence: 99%

Sequential Base-Promoted Annulation/Palladium-Catalyzed Domino 1,5-Enyne Arylation and Vinylation of α-Propargylaminohydrazones

et al. 2002

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2-Diazabuta-1,3-dienes represent versatile building blocks in organic synthesis because they offer easy access to a wide variety of heterocyclic compounds by 1,4-conjugate addition and subsequent cyclization reactions. [1] Moreover, Michael reaction adducts of the 1,2-diazabuta-1,3-diene system may act as nitrogen ligands [2] for transition metal catalysts, which leads to unusual reaction pathways. [3] In common with other Michael additions, 1,2-diazabuta-1,3dienes undergo divergent copper-promoted annulation reactions to form functionalized imidazolines/imidazoles under regiocontrol, whereas the base-promoted cyclization provides both 1-substituted and 1-unsubstituted 4-aminocarbonyl-1Hpyrazol-5(2H)-ones. [4] A variety of metal-catalyzed reactions of enynes, which involve a broad range of early and late transition metals, are of interest in the synthesis of functionalized carbo/heterocycles. [5] The classes of reaction that involve the metalcatalyzed functionalization of enynes include cycloisomerization, [6] reductive cyclization, [7] bismetallative cyclization, [8] carbonylative cyclizations, [9] and dimerization/cyclization. [10] One-pot domino reactions of enynes provide a valuable procedure for easy access to five-and six-membered heterocycles containing a 1,3-diene structure, which can lead to bicyclic compounds through in situ Diels ± Alder reactions. [11] Domino reactions are emerging as powerful strategies in modern synthetic organic chemistry, and the discovery of new reaction sequences able to produce functional compounds constitutes a challenge both from the academic and industrial points of view. [12] The a-propargylaminohydrazone adducts 1 a ± c (Scheme 1, Table 1), which contain a 1,4-diazo-1,6-azenyne system, turned out to be useful substrates for further metal-catalyzed processes. In this context, we investigated the palladiumcatalyzed arylation and vinylation reactions of a-propargyl-aminohydrazones. Here we report a new, efficient synthetic methodology for the preparation of (Z)-6-arylidene/vinylidene-6a-methyl-1,5,6a-tetrahydro-2H-pyrrolo[3,2-c]pyrazol-3-ones (for example, 3a ± h) through remarkable sequential base-promoted annulation/palladium-catalyzed, domino 1,5enyne arylation and vinylation reactions.The treatment of 1 a ± c with anhydrous piperidine in the presence of aryl iodide/triflate derivatives 2 a ± h and Pd(OAc) 2 /DPPF (Ac acetyl; DPPF 1,1'-bis(diphenylphosphanyl)ferrocene) catalytic system gave 3 a ± h in good yields (Scheme 1, Table 1). The structure of compounds 3 was confirmed by one-( 1 H, 13 C) and two-dimensional (COSY, HETCOR, NOESY) NMR spectral analysis, and by mass spectroscopy. NOESY experiments clearly demonstrate that the geometry of the exocyclic double bond is Z for all compounds 3 a ± h. Moreover, 1 H and 13 C NMR signals arising from the vinyl substituted pyrazolones 3 e ± h are split because of the presence of multiple isomers. Scheme 1. Reagents and conditions: 1) Pd(OAc) 2 , DPPF, piperidine, RT, 24 h. Spectroscopic data of new compounds can be found in...

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“…[4] A variety of metal-catalyzed reactions of enynes, which involve a broad range of early and late transition metals, are of interest in the synthesis of functionalized carbo/heterocycles. [5] The classes of reaction that involve the metalcatalyzed functionalization of enynes include cycloisomerization, [6] reductive cyclization, [7] bismetallative cyclization, [8] carbonylative cyclizations, [9] and dimerization/cyclization. [10] One-pot domino reactions of enynes provide a valuable procedure for easy access to five-and six-membered heterocycles containing a 1,3-diene structure, which can lead to bicyclic compounds through in situ Diels ± Alder reactions.…”

mentioning

confidence: 99%