- Reactions of 2,3-Dibromo-2-methylpropanamides Promoted by Potassium tert-Butoxide
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Abstract: 2,3-Dibromo-2-methylpropanamides with different substituents on the nitrogen atom were synthe-sized, and their transformations by the action of potassium tert-butoxide in THF were studied. 2,3-Dibromo-N-(4-methoxyphenyl)-2-methylpropanamide and 2,3-dibromo-N-(2,5-dibromo-4-methoxyphenyl)-2-methyl-propan-amide reacted with 1–2 equiv of t-BuOK to give the corresponding N-substituted 3-bromo-3-methyl- and 3-methylideneazetidin-2-ones with acceptable yields and selectivity. Increase of the amount of t-BuOK to 3–5 equiv led to significant reduction of the yield of vinyl bromides and 3-methylideneazetidin-2-ones. On the other hand, the reaction of 2,3-dibromo-N-(tert-butyl)-2-methylpropanamide with t-BuOK afforded 3-(tert-bu-toxymethyl)-1-tert-butylazetidin-2-one with a good yield and selectivity.
- Galeeva, A. M.,Miftakhov, M. S.,Selezneva, N. K.,Valiullina, Z. R.
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p. 1643 - 1649
(2021/12/13)
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- Ir(III)-catalyzed mild C-H amidation of arenes and alkenes: An efficient usage of acyl azides as the nitrogen source
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Reported herein is the development of the Ir(III)-catalyzed direct C-H amidation of arenes and alkenes using acyl azides as the nitrogen source. This procedure utilizes an in situ generated cationic half-sandwich iridium complex as a catalyst. The reaction takes place under very mild conditions, and a broad range of sp2 C-H bonds of chelate group-containing arenes and olefins are smoothly amidated with acyl azides without the intervention of the Curtius rearrangement. Significantly, a wide range of reactants of aryl-, aliphatic-, and olefinic acyl azides were all efficiently amidated with high functional group tolerance. Using the developed approach, Z-enamides were readily accessed with a complete control of regio- and stereoselectivity. The developed direct amidation proceeds in the absence of external oxidants and releases molecular nitrogen as a single byproduct, thus offering an environmentally benign process with wide potential applications in organic synthesis and medicinal chemistry.
- Ryu, Jaeyune,Kwak, Jaesung,Shin, Kwangmin,Lee, Donggun,Chang, Sukbok
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supporting information
p. 12861 - 12868
(2013/09/23)
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- Catalytic dicyanative 5-exo- And 6-endo-cyclization triggered by cyanopalladation of alkynes
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A stereoselective dicyanative 5-exo- and 6endo-cyclization using various enynes has been investigated. The mode of cyclization is critically controlled by the structure of the substrates. For example, N-allyl derivatives prefer 5-exo-cyclization, while methacryloyl amides are transformed to the corresponding lactams with tetra substituted carbons at the alpha-position via 6-endo-cyclization. Both reactions include syn-cyanopalladation to carbon≡carbon triple bonds in the initial step, and sequential cyclization followed by reductive elimination in one operation enables the construction of the highly functionalized nitrogen heterocycles. The scope of suitable substrates and a proposed mechanism are also described.
- Arai, Shigeru,Koike, Yuka,Nishida, Atsushi
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experimental part
p. 893 - 900
(2010/07/06)
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- INTERACTION OF ALKYLIDENE CARBENES WITH NITROSO COMPOUNDS
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The reaction of an alkylidenecarbene with 2-methyl-2-nitrosopropane results in various amides via the intermediacy of keteneimine N-oxide and aziridinone.
- Stang, Peter J.,Anderson, Gary H.
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p. 329 - 332
(2007/10/02)
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- Synthesis, fragmentations and rearrangements of 3-(1-haloalkyl) oxaziridines
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A variety of new 3-(1-haloalkyl)oxaziridines was synthesized by oxidation of α-chloro-, α-bromo-, α,α-dichloro-, α,α-dibromo- and α,α,α-trichloroaldimines with meta-chloroperbenzoic acid. Attempts to induce dehydrohalogenation into the elusive methyleneoxaziridines were unsuccessful. However, presumptive evidence is presented that 2-t-butyl-3-(trichloromethyl)oxaziridine is dehydrochlorinated into a transient methyleneoxaziridine, which underwent valence isomerization into an intermediate iminooxirane, the latter being fragmented into t-butyl isocyanide. Various types of reactions of the title compounds are reported. Among others, 2-alkyl-3-(1-chloro-1-methyl) ethyloxaziridines rearranged with methyllithium into 2-(N-alkyl)aminoisobutyraldehydes.
- De Kimpe, Norbert,De Corte, Bart
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p. 7345 - 7362
(2007/10/02)
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- Thermolysis and Some Reactions of 3-Alkyl-3,5-dihydro-5,5-dimethyl-4H-1,2,3-triazol-4-ones and 1-tert-Butyl-3,3-dimethyl-2-aziridinone. Is the Acyclic Aziridinone a Zwitterion?
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Solvent polarity influences only little the thermolysis of both aziridinone 2a (40 deg C) and dihydro-1,2,3-triazolone 1a (70 deg C) which quantitatively decompose into acetone and tert-butyl isocyanide (5a) (besides molecular nitrogen in the case of 1a).In contrast to earlier reports, 2a does not produce the α, β-unsaturated amide 7 on heating. Dimethylformamide converts 1a and 2a into the oxazolidinone -6.While solvolysis of both 1a and 2a in pure methanol predominantly yields the α-methoxyamide -10a, 1a and 2a react differently with sodium methoxide in methanol.This reagent converts 1a into 10a, as does methanol itself, but 2a into the α-aminoester 12.Small amounts of acetone and tert-butyl isocyanide (5a) are formed as by-products in almost all reactions.The results are consistent with the occurence as intermediate of the acyclic "non-Kekule"-molecule 3a, a diradical, which exhibits the same polarity as its precursors 1a and 2a.The intermediate 3a is trapped by the solvent (-> -6, 10a) or decomposes via the iminooxirane 4a into acetone and the isocyanide 5a.
- Quast, Helmut,Meichsner, Georg,Seiferling, Bernhard
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p. 217 - 224
(2007/10/02)
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- Electrochemistry of 2-Bromo-2-methylpropanamides. Reduction Mechanism and Cyclocoupling Reaction with Amide Solvents
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The electrochemical reduction of series of secondary and tertiary α-bromoisobutyramides has been studied in dipolar aprotic solvents.A carbanion is formed at the mercury electrode as a consequence of two-electron C-Br bond cleavage.Voltammetry and macroelectrolysis point to a self-protonation mechanism, the carbanion undergoing protonation by a parent molecule to yield the isobutyramide.Concurrently, tertiary 2-bromoamides undergo 1,2-elimination to yield an αβ-unsaturated amide, while secondary 2-bromoamides are deprotonated at the nitrogen atom, affording a bromo-containing anion.The decay of the latter is strongly dependent on the solvent and the substituent at nitrogen.In acetonitrile, elimination and fragmentation products are identified in the electrolysed solution.On the other hand, in N,N-dimethylformamide or N,N-dimethylacetamide, the bromo-containing anion is eventually cyclocondensed onto the carbonyl group of the amide solvent, to yield an oxazolidin-4-one derivative.Preliminary data suggest that an analogous cyclocoupling reaction takes place when the reduction is carried out in 1-methyl-2-pyrrolidone.
- Maran, Flavio,Vianello, Elio,D'Angeli, Ferruccio,Cavicchioni, Giorgio,Vecchiati, Giorgio
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