Substituted coumarin amidines: useful building blocks for the preparation of [1]benzopyrano[4,3-b]pyridin-5-one and [1]benzopyrano[4,3-d]pyrimidin-5-one derivatives
作者:Egle M. Beccalli、Alessandro Contini、Pasqualina Trimarco
DOI:10.1016/j.tet.2005.03.050
日期:2005.5
synthesis of [1]benzopyrano[4,3-b]pyridin-5-ones 4a–f and 4g–j starting from 3-formylcoumarin and 3-cyanocoumarin N-functionalized amidines 3a–f and 3g–j, respectively, was reported. The ring-closure reaction mechanism, under basic or acidic media, was proposed. Furthermore, the reaction of 3-formylamidines 3a,c–f with ammonium acetate gave good yields of 2-substituted [1]benzopyrano[4,3-d]pyrimidin-5-ones
New synthetic approach to [1]benzopyrano[4,3-b]pyridin-5-one derivatives
作者:Egle M. Beccalli、Alessandro Contini、Pasqualina Trimarco
DOI:10.1016/j.tetlet.2004.03.009
日期:2004.4
A new synthesis of [1]benzopyrano[4,3-b]pyridin-5-ones 4 was developed starting from 3-formyl-coumarin N-functionalized amidines 3. The reaction is based likely on the intramolecular cyclocondensation of the C-α amidinic carbanion in basic medium on the formyl group.
从3-甲酰基香豆素N-官能化am 3开始,开发了[1]苯并吡喃并[4,3 - b ]吡啶-5-酮4的新合成方法。该反应很可能是基于在甲酰基的碱性介质中C-α氨基碳负离子的分子内环缩合。
ν-Triazolines. Part 42. Study on the reactivity of 4,5-dihydro-1-(6-methyl-2-oxo-2H-pyran-4-yl)-5-morpholino-ν-triazoles. Synthetic approach to pyrano[4,3-b]pyrrol-4(1H)-ones
作者:Emanuela Erba、Donato Pocar、Pasqualina Trimarco
DOI:10.1039/b008531f
日期:——
Pyrolysis of 4-aryl-5-morpholino-4,5-dihydrotriazoles 3 affords two products: pyrano[4,3-b]pyrrol-4(1H)-ones 4 and arylacetamidines 5. The reaction mechanism of this transformation is discussed and reaction conditions optimized to enhance the formation of pyrrole-fused pyran-2-one derivatives 4. 2-Aminoaziridines are considered to be key intermediates in this transformation.
Inverse electron demand hetero-Diels–Alder reaction in preparing 1,4-benzodioxin from o-quinone and enamine
作者:Jinsong Zhang、Chris Taylor、Erich Bowman、Leo Savage-Low、Michael W. Lodewyk、Larry Hanne、Guang Wu
DOI:10.1016/j.tetlet.2013.09.013
日期:2013.11
A process for synthesizing 1,4-benzodioxin, through oxidation of a phenol to an o-quinone followed by treatment with an enamine, has been developed. Adduct stereochemistry is found to be retained via this one-pot reaction. The method uses hypervalent iodine reagent under mild conditions and is compatible with a wide scope of phenols and enamines. Published by Elsevier Ltd.
The First Rhodium-Catalyzed Anti-Markovnikov Hydroamination: Studies on Hydroamination and Oxidative Amination of Aromatic Olefins
作者:M. Beller、H. Trauthwein、M. Eichberger、C. Breindl、J. Herwig、T. E. Müller、O. R. Thiel
The first transition-metal-catalyzed regiospecific anti-Markovnikov hydroamination of aromatic olefins is reported. Styrene and substituted styrenes react with secondary aliphatic amines, especially morpholine and N-arylpiperazines, in the presence of cationic rhodium complexes to give 2-aminoethenylbenzene and 2-aminoethylbenzene derivatives. Cationic [Rh(cod)(2)]+BF4- and various phosphines (1:2-mixture) were employed as in situ catalysts. According to labeling experiments, there is no evidence that the hydroamination is a consecutive hydrogenation of a previously formed enamine. Hydroamination with simple secondary amines, for example piperidine, can also be achieved by the use of a higher olefin concentration and higher reaction temperatures than those given in previously published reaction procedures. Kinetic investigations of the major reaction pathway reveal that the reaction rate of the oxidative amination and the hydroamination is dependent on the styrene and on the catalyst concentration, and independent of the amine concentration. Experiments that employed deuterium-labeled amines (N-D) provided evidence that the mechanism involves an amine-activating pathway, The substituents on the styrene, the phosphine ligand, and the solvent influence the yield of the aminations and the enamine:alkylamine ratio.