共查询到20条相似文献,搜索用时 14 毫秒
1.
Mariola Zielinska-B?ajet 《Tetrahedron》2005,61(22):5235-5240
A new and simple method for the stereospecific synthesis of 3,5-disubstituted-4,5-dihydro-isoxazoles (chiral isoxazolines) from readily available oximes of chiral Michael adducts of thiophenol to chalcones is reported. An analogous reaction with the N-arylhydrazones of the Michael adduct gave nonracemic 1-(aryl)-3,5-diphenyl-4,5-dihydro-1H-pyrazoles (chiral pyrazolines), but these products are configurationally unstable. The key step of the synthesis is the ring-closure reaction, which occurs by a stereospecific intramoleculer nucleophilic substitution of thiophenoxide. 相似文献
2.
Attanasi OA De Crescentini L Favi G Filippone P Lillini S Mantellini F Santeusanio S 《Organic letters》2005,7(12):2469-2471
[reaction: see text] Here, we report the protocol for the preparation of new poly(ethylene glycol)-supported 1,2-diaza-1,3-butadiene. In addition, we discuss an application of this supported reagent in an efficient and environmentally friendly one-pot synthesis of 2-thiazol-4-one derivatives by reaction with thioamides. 相似文献
3.
Kleine T Fröhlich R Wibbeling B Würthwein EU 《The Journal of organic chemistry》2011,76(11):4591-4599
Unsymmetrical N,N'-bisalkylidene hydrazines 7a,b, 10a-c and 13, which are accessible in good to excellent yields from hydrazones 6, 9, and 12 and commercially available α,β-unsaturated carbonyl compounds, are converted into 3,4-diazaheptatrienyl anions 14a,b, 16a-c, and 18 by treatment with KO-t-Bu as base. These anionic species form pyridines 15a,b, 5,6-dihydrobenzo[h]quinolones 17a-c, and bipyridine 19 in moderate yields. We interpret thermodynamics and kinetics of these reactions by quantum chemical calculations and discuss this multistep anionic rearrangement, based on an electrocyclic ring formation with a Mo?bius aromatic transition structure 22, the N-N bond fission (25), and the 6-exo-trig cyclization (27) as key steps, considering the results of NICS and NBO-charge calculations. This novel anionic reaction sequence bears an interesting analogy to the mechanism of the (cationic) Fischer indole synthesis. Precursor 10c and product 16c could be characterized by X-ray diffraction. 相似文献
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Platas-Iglesias C Vaiana L Esteban-Gómez D Avecilla F Real JA de Blas A Rodríguez-Blas T 《Inorganic chemistry》2005,44(26):9704-9713
A detailed study of the electronic structure of seven-coordinate Mn(II), Co(II), and Ni(II) complexes with the lariat ether N,N'-bis(2-aminobenzyl)-1,10-diaza-15-crown-5 (L(1)) is presented. These complexes represent new examples of structurally characterized seven-coordinate (pentagonal bipyramidal) complexes for the Mn(II), Co(II), and Ni(II) ions. The X-ray crystal structures of the Mn(II) and Co(II) complexes show C(2) symmetries for the [M(L(1))](2+) cations, whereas the structures of the Ni(II) complexes show a more distorted coordination environment. The magnetic properties of the Mn(II) complex display a characteristic Curie law, whereas those of the Co(II) and Ni(II) ions show the occurrence of zero-field splitting of the S = 3/2 and 1 ground states, respectively. Geometry optimizations of the [M(L(1))](2+) systems (M = Mn, Co, or Ni) at the DFT (B3LYP) level of theory provide theoretical structures in good agreement with the experimental data. Electronic structure calculations predict a similar ordering of the metal-based beta spin frontier MO for the Mn(II) and Co(II) complexes. This particular ordering of the frontier MO leads to a pseudodegenerate ground state for the d(8) Ni(II) ion. The distortion of the C(2) symmetry in [Ni(L(1))](2+) is consistent with a Jahn-Teller effect that removes this pseudodegeneracy. Our electronic structure calculations predict that the binding strength of L(1) should follow the trend Co(II) approximately Mn(II) > Ni(II), in agreement with experimental data obtained from spectrophotometric titrations. 相似文献
6.
Chemistry of Heterocyclic Compounds - Diversity-oriented synthesis embodied in a strategy of pairing vinyl sulfonamide moiety with other functional groups resulted in an array of skeletally diverse... 相似文献
7.
Orazio A. Attanasi Silvia Bartoccini Gianluca Giorgi Fabio Mantellini Francesca R. Perrulli Stefania Santeusanio 《Tetrahedron》2010,66(27-28):5121-5129
Depending on the nature of the solvent, alcohol or DMF, N-phenylbenzamidine shows different nucleophilic behaviour towards the conjugated azo–ene system of 1,2-diaza-1,3-dienes. In alcohol it reacts as a nucleophile through the N-phenyl imino nitrogen affording spiro pyrroloimidazoles and 1,3-diphenyl-1H-imidazoles. In DMF, by contrast, it behaves as nucleophile mainly by means of the imino amidino nitrogen providing 2-phenylimidazole derivatives by loss of the aniline molecule. 相似文献
8.
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
9.
1-Isopropyl-3-tert-butyl-1,2-diaza-1,3-butadiene (I), which is formed as a result of the reaction of -chloropinacoline with isopropyl hydrazine, exists in the form of a mixture of cisoid and transold conformations and is extremely active in the diene synthesis with maleic anhydride, maleimide, dimethyl fumarate, and methyl vinyl ketone. The conformations of the derivatives obtained, which contain a 2-tetrahydropyridazine ring, were established on the basis of the PMR spectra. 1-Isopropyl-3-tert-butyl-trans-5,6-dicarbomethoxy-2-tetrahydropyrid-azine was obtained from dimethyl fumarate and I; this was confirmed by a comparison of data on it with the characteristics of the cis isomer, synthesized by the action of diazomethane on the anhydride of 1-isopropyl-3-tert-butyl-2-tetrahydropyridazine-5,6-dicarboxylic acid.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 124–128, January, 1973. 相似文献
10.
Orazio A. Attanasi Paolino Filippone Barbara Guidi Thomas Hippe Fabio Mantellini Lutz F. Tietze 《Tetrahedron letters》1999,40(52):827-9280
The first general protocol for the preparation of different polymer-bound 1,2-diaza-1,3-butadienes is reported. The utility of these supported reagents in the solid-phase synthesis of 4-triphenylphosphoranylidene-4,5-dihydropyrazol-5-ones by reaction with triphenylphosphine is presented. 相似文献
11.
Hideki Sakurai Toshiaki Kobayashi Yasuhiro Nakadaira 《Journal of organometallic chemistry》1978,162(3):C43-C47
Two new 1,2-disilacyclobutenes have been prepared by the reaction of tetramethyldisilene with acetylenes. Several reactions of these new 1,2-disilacyclobutenes including oxidation, silylene insertion, iron carbonyl insertion, and addition to acetylenes and dienes are reported. 相似文献
12.
Ly HV Konu J Parvez M Roesler R 《Dalton transactions (Cambridge, England : 2003)》2008,(26):3454-3460
Two heterocyclic cyclopentadienyl analogs with a CB2N2 skeleton, 4-methyl-1,2,3,5-tetraphenyl-1,2-diaza-3,5-diborolidine and 4-methyl-3,5-dimethylamino-1,2-diphenyl-1,2-diaza-3,5-diborolidine were prepared through cyclocondensation of the corresponding 1,1-bis(organochloroboryl)ethane with 1,2-diphenylhydrazine. The former diazadiborolidine featured a cyclopentadiene-like structure with short B-N bonds and a planar ring framework, while in the latter the B-N bonds were noticeably longer and the ring framework was considerably folded as a result of the interaction between boron and the electron donating NMe2 groups. The dimethylamino substituted diazadiborolidine could not be deprotonated due to the reduced acidity of the ring proton, however, the B-phenylated analog was easily deprotonated and the lithium, sodium and potassium 1,2-diaza-3,5-diborolyls were isolated and structurally characterized. The solid state structures of the lithium and sodium salts were similar, with an eta(1)-coordinated pi ligand and three THF molecules completing the coordination sphere of the metal. The potassium salt featured a highly unusual mono-dimensional polymeric structure with the metal pi-coordinated by the CB2N2 ligand and two of the phenyl groups on boron and nitrogen, and sigma-coordinated by one THF molecule. 相似文献
13.
Several 1,2,3-trialkyl-1,2-dihydroquinolines (4 and 5) were prepared from the reactions of N-alkylanilinomagnesium bromide (1 and 2) with aliphatic aldehydes (3). Solutions of these dihydroquinolines in carbon tetrachloride or chloroform gave the corresponding 1,2,3- trialkylquinolinium chlorides (10 and 11) in high yields. Alkali treatment of 1,3-dimethyl-2- ethylquinolinium chloride (10b) led to 1,3 - dimethyl - 2 - acetyl - 1,2 - dihydroquinoline (13), which was unstable and readily converted to 1,3-dimethyl-2-quinolone (6) in the air. 相似文献
14.
Starting from 1-tert-butyloxycarbonyl-3-methyl-4-ethoxycarbonyl-1,2-diaza-1,3-diene and β,β,β and α,β-substituted enamines a careful choice of solvents and temperatures allows the divergent synthesis of 5,6-dihydro-4H-pyridazines, 2-(1-N-boc-hydrazono-ethyl)-4-pyrrolidin-1-yl-but-3-enoic acid ethyl ester, and 1-amino-pyrroles. Moreover, some interesting conclusions about the mechanism(s) of the reaction have been drawn by careful analysis of products' structure and distribution. Thus, the reaction may proceed through a stereospecific [4+2] cycloaddition mechanism giving rise to 5,6-dihydro-4H-pyridazines or by simple addition or domino addition/cyclization pathways affording, respectively, 2-(1-N-boc-hydrazono-ethyl)-4-pyrrolidin-1-yl-but-3-enoic acid ethyl ester and 1-amino-pyrroles (formally the [3+2] cycloaddition product). 相似文献
15.
Reaction of 5-amino-4-alkyl(aryl or aralkyl)aminopyrimidines with PCl5 gives 2,2-dichloro-3-alkyl(aryl or aralkyl)-1,3-diaza-2-phospholo[4,5-d]pyrimidines, which on treatment with piperidine or morpholine are converted into the corresponding 2,2-diamino derivatives. The latter, on boiling in water or aqueous alcohol, give the dipiperidides or dimorpholides of the corresponding 5-pyrimidylamidophosphoric acids.Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 710–712, May, 1970. 相似文献
16.
Attanasi OA Favi G Filippone P Giorgi G Mantellini F Moscatelli G Spinelli D 《Organic letters》2008,10(10):1983-1986
The versatility of the Mukaiyama-Michael-type addition/heterocyclization of Danishefsky's diene with 1,2-diaza-1,3-butadienes was applied to the synthesis of both 4 H-1-aminopyrroles and 4,5 H-pyrazoles. Thus, the same reagents furnished different types of highly functionalized azaheterocycles essentially depending on their structure: as a matter of fact, R1 = COOR or CONR 2 differently affects the acidity of the proton at the adjacent carbon. An unexpected formation of 5 H-1-aminopyrroles from the reactions carried out in water was also observed. 相似文献
17.
Valdés Á Brillet J Grätzel M Gudmundsdóttir H Hansen HA Jónsson H Klüpfel P Kroes GJ Le Formal F Man IC Martins RS Nørskov JK Rossmeisl J Sivula K Vojvodic A Zäch M 《Physical chemistry chemical physics : PCCP》2012,14(1):49-70
An overview of a collaborative experimental and theoretical effort toward efficient hydrogen production via photoelectrochemical splitting of water into di-hydrogen and di-oxygen is presented here. We present state-of-the-art experimental studies using hematite and TiO(2) functionalized with gold nanoparticles as photoanode materials, and theoretical studies on electro and photo-catalysis of water on a range of metal oxide semiconductor materials, including recently developed implementation of self-interaction corrected energy functionals. 相似文献
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Aparicio D Attanasi OA Filippone P Ignacio R Lillini S Mantellini F Palacios F de Los Santos JM 《The Journal of organic chemistry》2006,71(16):5897-5905
The preparation of tetrahydropyrazines, dihydropyrazines, pyrazines, piperazinones, and quinoxalines by 1,4-addition of 1,2-diamines to 1,2-diaza-1,3-butadienes bearing carboxylate, carboxamide, or phosphorylated groups at the terminal carbon and subsequent internal heterocyclization is described. The solvent-free reaction of carboxylated 1,2-diaza-1,3-butadienes with the same reagents affords piperazinones, while phosphorylated 1,2-diaza-1,3-butadienes yield phosphorylated pyrazines. The solid-phase reaction of polymer-bound 1,2-diaza-1,3-butadienes with 1,2-diamines produces pyrazines. 相似文献
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