- Gold catalysis: Products and intermediates obtained from N-propargylcarboxamides bearing additional substituents on nitrogen
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The reaction of several propargylamide substrates with additional substituents on the nitrogen atom was investigated. Under aqueous conditions acyloxy-substituted allylammonium salts could selectively be obtained. Monitoring of the reactions by 1H NMR spectroscopy indicated the presence of an intermediate. Then switching to anhydrous reaction conditions allowed the isolation and characterization of these intermediates, oxazoliniminium species. Workup of the allylammonium salts under basic conditions led to an acyl transfer from the oxygen atom to the nitrogen atom, which proves that these products are not formed by a direct gold-catalysed hydration of the triple bond only, and at the same time nicely explains the selective monohydration of only one out of two triple bonds. A careful control of the conditions allows the synthesis of either oxazolinum salts oracyloxy-substituted enynes with an ammonium unit in the tether. The latter compounds are stable in the presence of the gold catalyst; they do not undergo a gold-catalysed enyne cycloisomerization. Copyright
- Hashmi, A. Stephen K.,Molinari, Lise,Rominger, Frank,Oeser, Thomas
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experimental part
p. 2256 - 2264
(2011/06/19)
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- Synthesis of oxazoles through Pd-catalyzed cycloisomerization-allylation of N-propargylamides with allyl carbonates
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In the presence of Pd2(dba)3-Cy3P catalyst, IPr·HCl salt [IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene], and Cs2CO3, N-propargylamides react with allyl carbonates to give 2,5-disubstituted o
- Saito, Akio,Iimura, Koichi,Hanzawa, Yuji
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scheme or table
p. 1471 - 1474
(2010/04/29)
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- Synthesis of cyclopropylpyrrolidines via reaction of N-allyl-N-propargylamides with a molybdenum carbene complex. Effect of substituents and reaction conditions
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Previous studies have demonstrated that group 6 carbene complexes react with α,ω-enynes to form vinylcyclopropane derivatives in good to excellent yield, and that the length and composition of the tether between the alkyne and the alkene often has a dramatic impact on the viability of this reaction pathway. The reactivity of allylpropargyl amine derivatives with pentacarbonyl(1-methoxypentylidene)molybdenum(0) (14a) was investigated in order to provide further insight into the steric and electronic factors controlling this reaction. Treatment of allylpropargyl amines with 14a failed to produce the desired cyclization products while treatment of allylpropargyl amides with 14a led to the expected cyclopropylpyrrolidine systems in good to excellent yields. Higher yields are obtained when the reaction is conducted in a sealed vial in the presence of atmospheric oxygen.
- Harvey, Daniel F.,Sigano, Dina M.
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p. 2268 - 2272
(2007/10/03)
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- Studies of the solid-phase Pauson-Khand reaction: Selective in-situ enone reduction to 3-azabicyclo[3.3.0] octanones
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The Smit-Caple DSAC Pauson-Khand cyclization of a series of N-protected allyl propargyl amines in the absence of oxygen gave rise to formation of the saturated azabicyclo[3.3.0]octanones in excellent yields. Standard cyclization in air gave mixtures of sa
- Becker, Daniel P.,Flynn, Daniel L.
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p. 2087 - 2090
(2007/10/02)
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- The Synthesis of Nitrogen Heterocycles via the Intramolecular Khand Reaction: Formation of Tetra- and Hexa-hydrocyclopentapyrrol-5(1H)-ones and Hexahydro-6H-2-pyrindin-6-ones
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Azabicyclooctenones and azabicyclononenones have been obtained by cyclisation of hexacarbonyldicobalt complexes of aza-heptenynes and -octenynes respectively.An unusual feature of the cyclisation of N-acyl-4-azahept-1-en-6-ynes is the extens
- Brown, Scott W.,Pauson, Peter L.
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p. 1205 - 1209
(2007/10/02)
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