- Lactam and Amide Acetals. 52. Reaction of Dimethylformamide Diethylacetal with 2,2-Dimethyl-4,6-dioxo-1,3-dioxane (Meldrum's Acid)
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Depending on the conditions of carrying out the reaction of dimethylformamide diethylacetal with the Meldrum's acid, either 2,2-dimethyl-4,6-dioxo-5-(N,N-dimethylaminomethylene)-1,3-dioxane or N,N,N',N'-tetramethylformamidinium salt of 2,2-dimethyl-4,6-dioxo-5-(2,2-dimethyl-4,6-dioxo-1,3-dioxan-5-yl)methylene-1,3-dioxane are formed.The two compounds can reacts with primary amines to form N-substituted 2,2-dimethyl-4,6-dioxo-5-aminomethylene-1,3-dioxanes.
- Stezhko, T. V.,Solov'eva, N. P.,Kuleshova, E. F.,Granik, V. G.
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- DMF in acetic anhydride: A useful reagent for multiple-component syntheses of merocyanine dyes
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A simple and highly efficient method for the preparation of merocyanine dyes is reported from mixtures of CH-acidic heterocycles and electron-rich dialkylaminothiazoles or methylene bases and various formylating reagents without isolation of the formylated intermediates. With the particularly useful formylation-condensation system of DMF in acetic anhydride and highly acidic 1,2,5,6-tetrahydro-2,6-dioxo-3-pyridinecarbonitriles 8, the transformations could be carried out as multicomponent reactions to give pure dyes 3-6 in 50-90% yield directly from the reaction mixtures.
- Wuerthner, Frank
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p. 2103 - 2113
(2007/10/03)
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- Synthesis of the microbial elicitor syringolide 2 multiply labelled with deuterium
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Multiply-deuterated syringolide 2 3 was prepared from D-xylulose and 8- bromooctanoic acid by a convergent route based on our previously reported biomimetic synthesis of this microbial elicitor. Key steps were the thermal acylation of the anisylidene-prot
- Henschke, Julian P.,Rickards, Rodney W.
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p. 211 - 220
(2007/10/03)
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- 3-Hydroxypyrroles and 1H-Pyrrol-3(2H)-ones. Part 2. Scope and Limitations of the Synthesis of Pyrrol-3-ones by Pyrolysis of Aminomethylene Meldrum's Acid Derivatives.
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Flash vacuum pyrolysis of N,N-disubstituted aminomethylene Meldrum's acid derivatives provides a route to 4,5-unsubstituted 1H-pyrrol-3(2H)-ones by a hydrogen-transfer-cyclisation sequence.Alkyl and aryl 1-substituted, 1,2-disubstituted, and 1,2,2-trisubstituted pyrrolones can be obtained.In competitive cases, there is little selectivity between hydrogen transfer from primary, secondary, or tertiary sites, although benzyl hydrogen atoms proved particularly reactive, giving a general synthesis of 2-phenyl-1H-pyrrol-3(2H)-ones.
- McNab, Hamish,Monahan, Lilian C.
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p. 863 - 868
(2007/10/02)
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- Proton Magnetic Resonance Studies of International Rotation, 10. Conformation and Stereodynamics of Dipolar Cyclic Enamines and Hydrazones
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2-Aminomethylene and 2-hydrazono derivatives 1-6 of carbocyclic and heterocyclic 1,3-dicarbonyl compounds which may form up to four rotational diastereoisomers were investigated by 1H and 13C NMR spectroscopy.The isomeric composition
- Koelle, Ulrich,Kolb, Bernd,Mannschreck, Albrecht
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p. 2545 - 2565
(2007/10/02)
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