Search results for "Alder"
showing 10 items of 273 documents
Gold catalyzed stereoselective tandem hydroamination–formal aza-Diels–Alder reaction of propargylic amino esters
2013
A gold-catalyzed tandem intramolecular hydroamination-formal aza-Diels-Alder reaction of propargylic amino esters is described. The overall process leads to the formation of a tetracyclic framework as a single diastereoisomer, with the creation of four bonds and five stereocenters.
Hydrothermal circulation on Ischia Island (Southern Italy), revealed by an integrated geochemical, geophysical and geological approach
2011
Volcano-hosted hydrothermal systems are complex geological objects, whose thorough characterisation requires extensive and interdisciplinary work. Indeed, even thought geological, geochemical and geophysical observations offer highly significant but independent information, only an integrated multidisciplinary approach can yield a comprehensive characterisation of the chemical/physical structure of hydrothermal systems. Notwithstanding the extensive application of geological, geochemical and geophysical techniques in geothermal research, there are only a few examples in the literature of concurrent use of the three techniques [Finizola et al., 2002; Zlotnicki et al., 2009]; these studies ov…
Tradition and rewrite: "El maestro de danzar", from Lope to Calderón
2018
Altres ajuts: FNS/00015_156044 En el presente artículo pretendo defender e ilustrar la influencia de El maestro de danzar, comedia de Lope de Vega, sobre la pieza homónima de Calderón, cuestión que ha suscitado opiniones dispares entre la crítica. Un análisis minucioso de ambos textos permite establecer paralelismos indiscutibles entre uno y otro, que ponen en evidencia la deuda de Calderón con el Fénix. Se detallan con precisión qué fragmentos se reescribieron y reutilizaron en la obra calderoniana, y se abordan asimismo las circunstancias y motivos que pudieron inducir a Calderón a llevar a cabo dicho proceso de reescritura, que el dramaturgo, lejos de ocultar, puso de manifiesto mediante…
Architecture of the NYT caldera and inner resurgent dome (Pozzuoli Bay, Campi Flegrei): new insights from seismic reflection and DInSAR data
2016
The Campi Flegrei and its offshore prolongation (Pozzuoli Bay) are a volcanic area dominated by a collapse caldera associated with the Neapolitan Yellow Tuff (NYT) eruption, occurred at ~15 ka BP, and by an intra-caldera resurgent dome. We present new insights into: a) the geometry and kinematics of faults formed inside the caldera, b) the architecture of the resurgent dome, and c) the relationship between the structural elements of the resurgent dome and ground deformations. This work is based on the integration of high- and ultra-high resolution seismic data, swath bathymetry data and ground deformation maps. The main results highlight that the NYT caldera, offshore, is characterized by a…
On the enhancement of stereoselection by cooperation between chiral auxiliaries. Asymmetric diels-alder reactions with fumaric acid bis ((S)-proline …
1989
Abstract Fumaric acid bis ((S)-proline benzyl ester) amide reacts with cyclopentadiene in thermal and Lewis acid catalyzed Diels-Alder reactions to give the cycloadducts with high yields and diastereomeric ratios up to 100:1.
ChemInform Abstract: Influence of Reactant Polarity on the Course of the Inverse-Electron-Demand Diels-Alder Reaction. A DFT Study of Regio- and Ster…
2010
The molecular mechanisms for the inverse-electron-demand Diels−Alder reactions between nitroethene and three substituted ethenes (propene, methyl vinyl ether, and dimethylvinylamine) to give the corresponding nitroso cycloadducts have been characterized with density functional theory methods using the B3LYP/6-31G* calculational level. On the basis of stability arguments and molecular orbital analysis relative rates, regioselectivity, and stereoselectivity, the presence of Lewis acid catalyst modeled by the BH3 system and the inclusion of solvent effects as a function of the nature of substituent in the dienophile fragment are analyzed and discussed. The ortho attack mode presents transition…
ChemInform Abstract: Gold Catalyzed Stereoselective Tandem Hydroamination-Formal Aza-Diels-Alder Reaction of Propargylic Amino Esters.
2013
The overall sequence of the tandem reaction presented here leads to nitrogen-containing tetracycles under formation of 4 bonds and five stereocenters, in most cases as single diastereoisomers.
Arynic species; effect of substituents on the reactivity of monosubstituted dehydrobenzenes
1986
Abstract Evidence is presented demonstrating the existence of free dehydrobenzenes in the thermal decomposition of diaryliodonium-2-carboxylates, and that o-benzyne itself and its 4-methyl-, 4-chloro-,4-bromo- and 4-nitro-derivatives are generated from insoluble polymer-bound precursors and trapped by a second solid phase in Diels-Alder reactions. Lifetimes for these elusive species are determined.
Ω-symmetric measures and related singular integrals
2021
ChemInform Abstract: Diels-Alder Reactions of in situ Generated N-Benzoylindolo-2,3- quinodimethane with Carbodienophiles.
2010
The indolo-2,3-quinodimethane (5), generated from 2,3-bis(bromomethyl)indole (4), was trapped with unsymmetrical carbodienophiles or N, N′-p-phenylenedimaleimide to furnish the 1,2,3,4-tetrahydrocarbazoles (6–9). [4 + 2]-Cycloaddition of 5 with tetracyanoethylene gave rise to the tetracyanocarbazole (10) and a subsequent product 11a or 11b. The Diels-Alder reaction of 5 with divinyl sulfone was regiospecific within the detection limits of HPLC analysis. Similarly, the reaction of 5 with N, N′-p-phenylenedimaleimide yielded solely the stereoisomer 9.