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1.
Giuliana Righi Giorgio Scotti Francesco Caruso Miriam Rossi Francesco Mecozzi Roberto Antonioletti Romina Pelagalli 《Tetrahedron》2013
The Lewis acid-catalyzed regioselective azidolysis of 2,3-three membered heterocyclic amines has been investigated. The results obtained demonstrated that using TMSN3 as a source of azide, the appropriate choice of Lewis acid allowed to obtain different regio- and stereocontrolled precursors of aminoalcoholic and triaminic sequences. Considering the occurrence of these moieties in the structure of many biologically active compounds, the present methodologies could represent a powerful tool in organic synthesis for the preparation of interesting molecules. 相似文献
2.
J. Srinivasa Rao G. Narahari Sastry 《International journal of quantum chemistry》2006,106(5):1217-1224
Ab initio quantum chemical calculations, G3B3, second‐order Møller–Plesset (MP2), and the hybrid density functional method B3LYP were employed to compute the proton affinities of 24 heterocyclic amines. A range of basis sets are employed, starting from double‐ζ polarization quality to triple‐ζ quality basis set with augmented diffuse and polarization function. Experimental values were used to calibrate the performance of various theoretical models. The regioselectivity for the protonation has been unambiguously established by performing B3LYP/6‐31G* calculations on the possible putative sites of attack. For the given series of compounds the performance of B3LYP/6‐31++G** and G3B3 levels of theory have been in excellent agreement with the experimental results with the deviations are of the order comparable with the experimental error. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 相似文献
3.
Zikri Altun Erdi A. Bleda Carl Trindle Jason Wang 《International journal of quantum chemistry》2014,114(10):675-687
N‐heterocyclic carbenes (NHCs) based on imidazole‐2‐ylidene ( 1 ) or the saturated imidazolidine‐2‐ylidene ( 2 ) scaffolds are long‐lived singlet carbenes. Both benefit from inductive stabilization of the sigma lone pair on carbon by neighboring N atoms and delocalization of the N pi lone pairs into the nominally vacant p‐pi atomic orbital at the carbene carbon. With thermochemical schemes G4 and CBS‐QB3, we estimate the relative thermodynamic stabilization of smaller ring carbenes and acyclic species which may share the keys to NHC stability. These include four‐membered ring systems incorporating the carbene center, two trivalent N centers, and either a boron or a phosphorus atom to complete the ring. Amino‐substituted cyclopropenylidenes have been reported but three‐membered rings containing the carbene center and two N atoms are not known. Our calculations suggest that amino‐substituted cyclopropenylidenes are comparable in stability to the four‐membered NHCs but that diazacyclopropanylidenes would be substantially less effectively stabilized. Concluding the series are acyclic carbenes with and without neighboring N atoms and a series of “two‐membered ring” azapropadienenylidene cations of form :C?N?W with W = an electron‐withdrawing agent. We have studied W = NO2, CH2(+), CF2(+), and (CN)2C(+). Although these systems display a degree of stabilization and carbene‐like electronic structure, the stability of the NHCs is unsurpassed. © 2014 Wiley Periodicals, Inc. 相似文献
4.
Peter Nesvadba Lucienne Bugnon Rosemarie Sift 《Journal of polymer science. Part A, Polymer chemistry》2004,42(13):3332-3341
The synthesis of new 7‐membered diazepanone alkoxyamines [2,2,7,7‐tetramethyl‐1‐(1‐phenyl‐ethoxy)‐[1,4]diazepan‐5‐one ( 3 ) and 2,7‐diethyl‐2,3,7‐trimethyl‐1‐(1‐phenyl‐ethoxy)‐[1,4]diazepan‐5‐one ( 8 )] through the Beckmann rearrangement of piperidin‐4‐one alkoxyamines was developed. Both 3 and 8 were evaluated as initiators and regulators for the nitroxide‐mediated radical polymerization of styrene and n‐butyl acrylate. 8 , a sterically highly hindered alkoxyamine readily available as a crystalline solid, allowed the fast and controlled polymerization and preparation of polymers with low polydispersity indices (1.2–1.4) up to a degree of polymerization of about 100. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3332–3341, 2004 相似文献
5.
Maria‐Evgenia Kourti Georgios C. Vougioukalakis Nikos Hadjichristidis Marinos Pitsikalis 《Journal of polymer science. Part A, Polymer chemistry》2011,49(11):2520-2527
The cationic ring‐opening polymerization of 2‐methyl‐2‐oxazoline and 2‐phenyl‐2‐oxazoline was efficiently used using bis(η5‐cyclopentadienyl)dimethyl zirconium, Cp2ZrMe2, or bis(η5‐tert‐butyl‐cyclopentadienyl)dimethyl hafnium in combination with either tris(pentafluorophenyl)borate or tetrakis(pentafluorophenyl)borate dimethylanilinum salt as initiation systems. The evolution of polymer yield, molecular weight, and molecular weight distribution with time was examined. In addition, the influence of the initiation system and the monomer on the control of the polymerization was studied. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 000: 000–000, 2011 相似文献
6.
Bungo Ochiai Kouichi Yoshii Daisuke Nagai Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2005,43(5):1014-1018
The cationic ring‐opening polymerization of a seven‐membered cyclic monothiocarbonate, 1,3‐dioxepan‐2‐thione, produced a soluble polymer through the selective isomerization of thiocarbonyl to a carbonyl group {? [SC(C?O)O(CH2)4]n? }. The molecular weights of the polymer could be controlled by the feed ratio of the monomer to the initiators or the conversion of the monomer during the polymerization, although some termination reactions occurred after the complete consumption of the monomer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1014–1018, 2005 相似文献
7.
Alexandru C. Razus Liviu Birzan Oana Zaharia Cristian Enache 《Journal of heterocyclic chemistry》2008,45(4):1139-1147
2‐(Azulen‐1‐yl)‐4,6‐diphenyl substituted pyranylium salts, pyridinium salts and pyridines were efficiently synthesized and the new obtained compounds were completely characterized. Comparative structural analysis between these compounds and their corresponding isomers that contain the azulen‐1‐yl moiety in the 4‐position of the heterocycle, were carried out. These studies are based on calculated dihedral angles formed between central heterocycle and the aromatic substituents and on the obtained electronic and NMR spectra. Due to the restriction in the rotation around azulenyl‐pyridinium bond produced by the quaternary nitrogen substituent, in the herein reported pyridinium salts, the substitution groups of the quaternary nitrogen atom are prochiral. This property leads to the non‐equivalence of gem‐protons or gem‐methyl groups of N‐substituents in the 1H nmr spectra of the synthesized pyridinium salts. 相似文献
8.
Song Yang Bao‐An Song Hua Zhang De‐Yu Hu Lin‐Hong Jin Gang Liu 《Journal of heterocyclic chemistry》2004,41(4):617-619
An environmentally benign and efficient process for the preparation of 1‐(2,3,4‐trimethoxyphenyl)‐2‐substituted heterocyclic thio ethanone derivatives was achieved by the reactions of mercapto compounds with 2‐bromo‐1‐(2,3,4‐trimethoxyphenyl)ethanone in water mediated by indium in very high yields. Antifungal activities of the compounds were examined and moderate activity was obtained. 相似文献
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Ivan Poto
k Jn Imrich Ivan Danihel Jozef Koíek Karel Douglas Klika 《Acta Crystallographica. Section C, Structural Chemistry》2010,66(2):o87-o92
Two methyl derivatives, five‐membered methyl 2‐{2‐[2‐(9,10‐dihydroacridin‐9‐ylidene)‐1‐methylhydrazinyl]‐4‐oxo‐4,5‐dihydro‐1,3‐thiazol‐5‐ylidene}acetate, C20H16N4O3S, (I), and six‐membered 2‐[2‐(9,10‐dihydroacridin‐9‐ylidene)‐1‐methylhydrazinyl]‐4H‐1,3‐thiazin‐4‐one, C18H14N4OS, (II), were prepared by the reaction of the N‐methyl derivative of 4‐(9,10‐dihydroacridin‐9‐ylidene)thiosemicarbazide, C14H12N4S, (III), with dimethyl acetylenedicarboxylate and methyl propiolate, respectively. The crystal structures of (I), (II) and (III) are molecular and can be considered in two parts: (i) the nearly planar acridine moiety and (ii) the singular heterocyclic ring portion [thiazolidine for (I) and thiazine for (II)] including the linking amine and imine N atoms and the methyl C atom, or the full side chain in the case of (III). The structures of (I) and (II) are stabilized by N—H...O hydrogen bonds and different π–π interactions between acridine moieties and thiazolidine and thiazine rings, respectively. 相似文献
11.
Daisuke Nagai Kensuke Yokota Takuma Ogawa Bungo Ochiai Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2008,46(2):733-739
Cationic ring‐opening copolymerization behavior of trioxane (TOX) and a seven‐membered cyclic carbonate, 1,3‐dioxepan‐2‐one (7CC) is described. When TOX and 7CC were cationically copolymerized under various feed ratios using trifluoromethane sulfonic acid (TfOH) as an initiator in nitrobenzene at 30 °C, 7CC was consumed faster than TOX and the decarboxylation was accompanied to afford the corresponding polyacetal–polycarbonate type copolymers containing poly(oxytetramethylene) units. The copolymer composition could be controlled by the feed ratio of 7CC, whose increase resulted in the high copolymer composition of the 7CC unit. The solubility of the copolymers increased as the increase of the 7CC content. Thermogravimetric, size‐exclusion chromatographic, and X‐ray analyses of the copolymers suggest that the sequences of the copolymer chains consist of the segments containing the units originated from 7CC and those with TOX unit‐rich compositions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 733–739, 2008 相似文献
12.
Nobukatsu Nemoto Fumio Sanda Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2001,39(9):1305-1317
This work deals with the cationic ring‐opening polymerization of the ester‐substituted cyclic carbonates 5‐methyl‐5‐benzoyloxymethyl‐1,3‐dioxan‐2‐one ( CC1 ) and 4‐benzoyloxymethyl‐1,3‐dioxan‐2‐one ( CC4 ). The polymerization was carried out with trifluoromethanesulfonic acid, methyl trifluoromethanesulfonate, boron trifluoride etherate, or methyl iodide as the initiator. The reactivity of CC1 and CC4 was higher than that of 5,5‐dimethyl‐1,3‐dioxan‐2‐one, which had no ester moiety. These results suggest that this ring‐opening polymerization was accelerated by the intramolecular ester group. CC1 showed a higher polymerizability than CC4 , affording a polymer with a higher molecular weight. Additionally, using methyl iodide as the initiator was effective for increasing the molecular weight of the obtained polycarbonate and decreasing decarboxylation. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1305–1317, 2001 相似文献
13.
The synthesis of pyrido[1,2‐a]indolium perchlorates 8,11 from 2,4,6‐triarylpyrylium perchlorates 1 and 2‐methyl‐3H‐indoles 6,9 in the presence of a basic condensing agent (anhydrous sodium acetate, piperidine acetate, triethylamine/acetic acid, triethylamine) in ethanol by a 2,4‐[C3+C2N] pyrylium ring transformation is reported. Spectroscopic data of the transformation products and their mode of formation are discussed. 相似文献
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The ring enlargement of 1‐benzyl‐2,5‐dihydro‐1H‐phosphole oxide ( 1 ) via the corresponding 2‐phosphabicyclo[3.1.0]hexane 2‐oxide ( 2 ) afforded, depending on the conditions, the double bond isomers ( A and B ) of 1,2‐dihydrophosphinine oxide 4 or that of 3‐substituted 1,2,3,6‐tetrahydrophosphinine oxides 5 and 6 . Dihydrophosphinine oxides ( 4 ) were suitable starting materials for 1,2,3,4,5,6‐hexahydrophosphinine oxide 7 and 1,2,3,6‐tetrahydrophosphinine oxide 8 obtained by reductive approaches and for the double bond isomers ( A and B ) of 2‐phosphabicyclo[2.2.2]octadiene 2‐oxide 9 and phosphabicyclooctene oxide 10 prepared in Diels–Alder cycloaddition. Precursor 9 was utilized in the fragmentation‐related phosphorylation of alcohols. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:28–34, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20363 相似文献
17.
. H. Üngren M. Samaci Y. Akamur C. Arici D. Ülkü 《Journal of heterocyclic chemistry》2004,41(2):151-155
The Wittig reaction of 2,3‐dihydro‐4‐(4‐methoxybenzoyl)‐5‐(4‐methoxyphenyl)‐furan‐2,3‐dione (1) with methyl (triphenylphosphoranylidene)acetate (2) stereo‐ and regioselectively afforded methyl (Z)‐[2,3‐dihydro‐4‐(4‐methoxybenzoyl)‐5‐(4‐methoxyphenyl)‐3‐oxofuran‐2‐ylidene]acetate (3) in good yield. The reactions of 3 with primary amines (4a‐k) gave corresponding 1‐substituted 2,3‐dihydro‐1Hpyrrol‐3‐ones (5a‐k). 相似文献
18.
Seiji Yamaguchi Toshiharu Katsuki Hajime Yokoyama Yoshiro Hirai 《Journal of heterocyclic chemistry》2001,38(2):511-514
Some 2‐isopropenyl‐2,3‐dihydronaphtho[2,3‐b]furan‐4,9‐diones la‐f,b',f were prepared by one‐step cyclizations of 2‐hydroxy‐1,4‐naphthoquinones 2a‐f with 1,4‐dibromo‐2‐methyl‐2‐butene ( 3 ). 相似文献
19.
The hitherto unreported oxazastibinanes 3 have been synthesized by the sodium borohydride reduction of 3‐phenyl‐1‐arylamino‐3‐oxopropane ( 1 ) and subsequent cyclization of the disodium salt of 3‐phenyl‐1‐arylamino‐3‐hydroxypropane ( 2 ) with R3SbBr2 (R = Ph, p‐tolyl, or mesityl). These compounds have been characterized by elemental analyses, molecular weight determination, and by IR, far IR, 1H, and 13C NMR spectral studies. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:417–420, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10155 相似文献
20.
Yi‐Zhi Li Rong‐Bin Dai An‐Xin Wu Min Wang Qin‐Xi Li Gang‐Chun Sun Liu‐Fang Wang Chun‐Gu Xia 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(10):e455-e456
The title compound, C22H20O6, has a central double bond of length 1.3694 (12) Å. Two benzene rings, lying on different sides of the diethyl 2‐butenedioate main chain, are almost parallel to each other and nearly perpendicular to the main chain. In the unit cell, two symmetry‐equivalent molecules are in general positions and two molecules lie on inversion centres. 相似文献