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41.
Easily accessible cycloalkenyl-1-diazenes and β-dicarbonyl compounds are converted in one-pot into previously unknown functionalized fused cycloalkenyliden-pyrroles of different sizes. The domino reaction proceeds through a base-catalyzed conjugate addition/cyclization/elimination sequence. 相似文献
42.
Attanasi OA De Crescentini L Favi G Filippone P Giorgi G Mantellini F Santeusanio S 《The Journal of organic chemistry》2003,68(5):1947-1953
Alpha-substituted hydrazones obtained from 1,2-diaza-1,3-butadienes and methylenic or methinic activated substrates gave rise to a wide range of cyclic compounds. In particular, in the presence of thionyl chloride as solvent-reagent, they were transformed into 1,2,3-thiadiazoles,(1) with selenium oxychloride in new 4-substituted 2,3-dihydro-1,2,3-selenadiazoles, while with selenium dioxide, they were transformed into 4-substituted 1,2,3-selenadiazoles. We have also examined the nucleophilic behavior of 1,2,3-thiadiazole 4a in the reaction with 1,2-diaza-1,3-butadienes that produced, under basic conditions, 4-hydrazono-1-(1,2,3-thiadiazolyl)pentane derivatives. This event represents an interesting example of stereoselective synthesis because it leads exclusively to the formation of the RR/SS racemic mixture. These latter compounds, treated with thionyl chloride, gave the corresponding 1,3-di-1,2,3-thiadiazolylpropane derivatives, while with sodium methoxide they afforded 1,2,3-thiadiazolyl-2-oxo-2,3-dihydro-1H-pyrrole systems. 相似文献
43.
Attanasi OA Favi G Filippone P Golobic A Stanovnik B Svete J 《The Journal of organic chemistry》2005,70(11):4307-4313
We observed a nucleophilic attack by the ene-amino carbon of 3-dimethylaminopropenoates at the terminal carbon of the azo-ene system of 1,2-diaza-1,3-butadienes. In tetrahydrofuran at 65 degrees C, this attack produced 1-aminopyrrolines with a high degree of cis-stereoselectivity by means of an unusual zwitterionic adduct intermediate followed by intramolecular ring closure. In toluene under reflux, 1-aminopyrrolines produced oxazoline-fused 1-aminopyrrolines. Oxazoline-fused 1-aminopyrrolines were directly obtained by reaction of 1,2-diaza-1,3-butadienes with 3-dimethylaminopropenoates in toluene under reflux. The ring opening of oxazoline-fused 1-aminopyrrolines in acidic or basic media provides highly substituted 1-aminopyrroles. 5-Unsubstituted 1-aminopyrrole derivatives were obtained from 1-aminopyrrolines under basic conditions by loss of dimethylamino and ester groups. We discuss the plausible mechanisms of the ring closure and opening. 相似文献
44.
Orazio A. Attanasi Graziano Baccolini Lucia De Crescentini Paolino Filippone 《Tetrahedron》2008,64(28):6724-6732
The reaction of 1,2-diaza-1,3-butadienes with dialkyl phenylphosphonites under solvent-free conditions proceeds via zwitterionic intermediate and gives, by precipitation, the stable ylidic α-phosphanylidene-hydrazones that, in turn, can be transformed into the corresponding 3-phenyl-2H-1,2,3λ5-diazaphospholes. The latter compounds are converted by hydrolytic cleavage in methanol-water (95:5) into E-hydrazonophosphonates that are useful for the preparation of the corresponding β-ketophosphonates and 4-[alkoxy(phenyl)phosphoryl]-1,2-diaza-1,3-butadienes. These peculiar 1,2-diaza-1,3-butadienes, bearing an alkoxy(phenyl)phosphoryl group on the carbon atom in position 4 are also able to add different nucleophiles, such as methanol or thiourea, giving 2-[alkoxy(phenyl)phosphoryl]-2-methoxyhydrazones and 5-phosphinate-substituted thiazol-4-ones, respectively. 相似文献
45.
OrazioA. Attanasi Lucia DeCrescentini Paolino Filippone Francesco Fringuelli Fabio Mantellini Mizio Matteucci Oriana Piermatti Ferdinando Pizzo 《Helvetica chimica acta》2001,84(2):513-525
The cycloadditions of (E)‐3‐diazenylbut‐2‐enes 1 with a variety of alkenes 2 – 6 were carried out in water as well as in organic solvents. The reactions were always faster in heterogeneous aqueous medium than in the organic solvents. These conjugated diazenyl‐alkenes behave mainly as heterodienes, and the Diels‐Alder adducts are the sole or at least main reaction products. Pyrroles derived from zwitterionic [3+2] cycloaddition reactions were observed in some cases. The cycloaddition of 1a with (+)‐2‐(ethenyloxy)‐3,7,7‐trimethylbicyclo[4.1.0]heptane ( 5 ) is the first example of an asymmetric `inverse electron‐demand' Diels‐Alder reaction carried out in pure water. 相似文献
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47.
Orazio A. Attanasi Silvia Bartoccini Gianfranco Favi Gianluca Giorgi Francesca R. Perrulli Stefania Santeusanio 《Tetrahedron》2012,68(2):608-613
1,2-Diaza-1,3-dienes (DDs) undergo, under neutral conditions, N-nucleophilic attack from a 4-ethoxycarbonylisoxazol-5-one derivative. The first aza-Michael addition is followed by an intramolecular second, affording a fused heterobicyclic system that, upon ring opening and decarboxylation processes, gives rise to novel substituted imidazoles with an acetate functionality in the 2-position. On the contrary, under the same reaction conditions, 3-phenylisoxazol-5-one provides a double Michael addition at two units of DD involving first the C-4 and then the N-2 of the heterocycle. The resulting diadduct spontaneously undergoes ring-opening/ring-closing process that concludes with a ring enlargement of the heterocycle providing the 1,3-oxazin-6-one derivative. 相似文献
48.
Orazio A. Attanasi Maurizio D’Auria Paolino Filippone Rachele Pucciariello 《European Polymer Journal》2008,44(8):2545-2550
Photochemical and anionic polymerizations of 1,2-diaza-1,3-butadienes are described. Photochemical polymerization was smoothly performed by irradiation of some 1-aminocarbonyl-1,2-diaza-1,3-butadienes with high pressure mercury arc (λ = 300 nm) in the presence of allyltributylstannane. Molecular weights (Mw) in the range 14.6-559 × 102 g/mol were obtained. The TGA curve revealed a first weight loss starting at about 200 °C of some 85%, and a second starting at about 300 °C. The DSC showed the glass transition (Tg) at about −34 °C. Anionic polymerization was performed by treatment of some 1-alkoxycarbonyl-1,2-diaza-1,3-butadienes with n-butyllithium. Molecular weights (Mw) in the range 8.44-242 × 102 g/mol were obtained. 相似文献
49.
Attanasi OA Bartoccini S Favi G Giorgi G Perrulli FR Santeusanio S 《The Journal of organic chemistry》2012,77(2):1161-1167
By highly efficient, one-pot, three-component reactions, combining one set of 1,2-diaza-1,3-dienes (DDs), primary amines, and isothiocyanates in a different sequential order of addition, heterocyclic skeletal diversity can be achieved. The key feature discriminating the different heterocyclic core formation is the availability of the N or S heteronucleophile to give the first Michael addition step affording regioselective substituted 2-thiohydantoins or 2-iminothiazolidinones. The hydrazone or enehydrazino side chain at the 5-position of both heterocycles represents a valuable functionality to reach novel 5-hydroxyethylidene derivatives difficult to obtain by other methods. 相似文献
50.