21731-13-5Relevant academic research and scientific papers
Aza-annulation of enaminones with crotonyl chloride - formal reversal of regioselectivity
Murphy, James P.,Hadden, Mark,Stevenson, Paul J.
, p. 11827 - 11834 (1997)
The regiochemistry of aza-annulation of enaminones with a,β-unsaturated acid chlorides bearing hydrogen atoms on the γ-carbon is reversed when triethylamine is used as mediator. When the reaction was carried out at lower temperatures a 3-acyl β,γ-unsaturated compound could be isolated which cyclised to the desired product under thermal or basic conditions. The nature of this intermediate strongly suggests that a vinyl ketene is the active acylating agent.
General, mild and efficient synthesis of β-enaminones catalyzed by ceric ammonium nitrate
Sridharan, Vellaisamy,Avenda?o, Carmen,Menéndez
, p. 881 - 884 (2008/02/02)
Ceric ammonium nitrate catalyzes the reaction between aromatic or aliphatic primary amines and a variety of β-dicarbonyl compounds, including β-ketoesters, β-ketothioesters and β-diketones. The reaction proceeds smoothly at room temperature in short react
Research on heterocyclic compounds. XLIII. Synthetic studies on 1,4-dihydropyridine derivatives
Rimoli, Maria Grazia,Avallone, Lucia,Zanarone, Serena,Abignente, Enrico,Mangoni, Alfonso
, p. 1117 - 1122 (2007/10/03)
In order to obtain N-benzyl-3,5-dicarbethoxy-2,6-dimethyl-4-phenyl-1,4-dihydropyridine 1 as a lead compound of pharmacological interest, the classical Hantzsch synthetic method and the modified Collie procedure were used. However, only a very low yield of
The CSIC [carbanion mediated sulfonate (sulfonamido) intramolecular cyclization] reaction: Scope and limitations
Marco, Jose L.,Ingate,Chinchon
, p. 7625 - 7644 (2007/10/03)
The CSIC (Carbanion-mediated Sulfonate-Sulfonamide-Intramolecular Cyclization) reaction has been extended to new carbonyl containing substrates, showing the scope and limitations of this process. Suitable derivatives of ketones (e.g acetophenone (1)), β-keto esters (e.g ethyl acetoacetate (4)), γ-keto esters (e.g ethyl 2-oxocyclohexaneacetate (5) and ethyl levulinate (6)) proved reluctant to undergo this protocol. Cyclopropyl methyl ketone (2) gave the heterocycle (3), only in the 'sulfonamide' synthetic sequence of the CSIC reaction. Cyclic azaketones (e.g tropinone (7)) fated also, but 4-piperidones (9, 10) afforded the novel 3,8- disubstituted 4-amino-8-aza-1-oxa-2-thiaspiro[4.5]dec-3-ene 2,2-dioxide (12, 15a-c) and 8-substituted 4-amino-1,8-diaza-2-thiaspiro[4.5]dec-3-ene 2,2- dioxide (18a, 18b, 21a, 21b) ring systems; the former compounds are the first examples of such ring systems substituted at the 3-position, whereas the latter represent the first ever representatives of spiro fused systems containing the 4-amino-2,3-dihydroisothiazole 1,1-dioxide moiety. Base promoted (NaH or DBU) cyclization of precursors 11b, 14a-c, 17b, 17c and 20 give the final adducts in good overall yield. Finally, we were unsuccessful with some conveniently functionalized anthranilonitrile derivatives (8a-d), in an attempt to extend the CSIC reaction to β-aminonitriles. As a result of these studies the substrate dependent reactivity in the CSIC reaction has been analyzed in depth and some restrictions and limitations have been observed and discussed.
On the Mechanism of Pyrrole Formation in the Knorr Pyrrole Synthesis and by Porphobilinogen Synthase
Fabiano, Emmanuel,Golding, Bernard T.
, p. 3371 - 3376 (2007/10/02)
Attempts to synthesise a derivative of N-vinylaminoethanal either by oxidation of the corresponding alcohol or by hydrolysis of the corresponding dithioacetal were unsuccessful, but such derivatives were characterised by 1H and 13C NMR spectroscopy of reactions between ethyl 2-aminoacetoacetate and an excess of ethyl acetoacetate, leading to diethyl 2,4-dimethylpyrrole-3,5-dicarboxylate.
