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21.
The largest discrete octadecameric architecture based on a lanthanide ion has been found in the crystal structure of a La{N,N'-bis(2-pyridylmethyl)-N,N'-1,2-ethanediylbis(D-alaninate)} complex. 相似文献
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Ito S Nomura A Morita N Kabuto C Kobayashi H Maejima S Fujimori K Yasunami M 《The Journal of organic chemistry》2002,67(21):7295-7302
The Diels-Alder reaction of di-2-azulenylacetylene with tetraphenylcyclopentadienone afforded 7,8,9,10-tetraphenyldiazuleno[2,1-a:1,2-c]naphthalene in one pot via autoxidation of the presumed 1,2-di-2-azulenylbenzene derivative. In contrast, a similar reaction of bis(1-methoxycarbonyl-2-azulenyl)acetylene with tetraphenylcyclopentadienone gave the 1,2-di-2-azulenylbenzene derivative. The following cyclodehydrogenation reaction of the benzene derivative with iron(III) chloride afforded diazuleno[2,1-a:1,2-c]naphthalene 6,11-bismethoxycarbonyl derivative. The redox behavior of these novel diazuleno[2,1-a:1,2-c]naphthalenes was examined by cyclic voltammetry (CV). These compounds exhibited two-step oxidation waves at +0.22 to +0.71 V upon CV, which revealed the formation of a radical cation and dication stabilized by the fused two azulene rings under the electrochemical oxidation conditions. Since the 1,2-di-2-azulenylbenzene derivative was oxidized at higher oxidation potentials (+0.83 and +1.86 V), the fusion of the two azulene rings to naphthalene increased electron-donating properties because of the formation of a closed-shell dicationic structure. Formation of the radical cation was characterized by UV-vis spectroscopy under the electrochemical oxidation conditions, although no evidence was obtained for the presumed dication under the conditions of the UV-vis spectroscopy measurement. 相似文献
24.
[reaction: see text] Inclusion ability of thiacalix[4]arenetetrasulfonate (TCAS) toward water-miscible organic molecules such as alcohols, ketones, cyclic ethers, and so on was studied by salting-out of the inclusion complex. NMR spectra of the recovered precipitates showed size selectivity to include the guest molecules. X-ray crystallographic analyses of TCAS salts including acetone and 1,4-dioxane suggested that guests are retained with the aid of cation coordination and H-bonding. 相似文献
25.
Chiral cationic palladium[bond]phosphinooxathiane complexes have been found to be effective catalysts for enantioselective Diels-Alder (DA) reaction of cyclopentadiene with acyl-1,3-oxazolidin-2-ones to give the corresponding DA adducts in good yield and high enantioselectivity up to 93% ee. 相似文献
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Nakano H Takahashi K Okuyama Y Senoo C Tsugawa N Suzuki Y Fujita R Sasaki K Kabuto C 《The Journal of organic chemistry》2004,69(21):7092-7100
Cationic palladium (Pd)- and platinum (Pt)-phosphinooxazolidine catalysts 13a-c, 15a-d, 17a-c, and 19a-c were prepared from phosphinooxazolidine ligands 1-3, MCl(2) (M = Pd and Pt), and counterions, and the activities of the catalysts in the asymmetric Diels-Alder (DA) reactions of cyclic or acyclic dienes with imide dienophiles were investigated. These catalysts demonstrated high levels of catalytic activity. The cationic Pd-POZ complex 13c provided particularly excellent enantioselectivity (98% ee) in the DA reactions of cyclopentadiene with acryloyl-, crotonyl-, and fumaroyl-1,3-oxazolidin-2-ones (20a-c). 相似文献
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Morohashi N Noji S Nakayama H Kudo Y Tanaka S Kabuto C Hattori T 《Organic letters》2011,13(13):3292-3295
Powdery crystals of p-tert-butylthiacalix[4]arene (2) selectively include EtOH from 1:1 mixtures of MeOH-EtOH and EtOH-PrOH, and EtCO(2)H from HCO(2)H-EtCO(2)H. On the other hand, no acid is included from HCO(2)H-MeCO(2)H, even though MeCO(2)H is included from the neat acid. The origins of these phenomena are discussed based on X-ray analysis of inclusion crystals prepared separately by crystallization. 相似文献
30.
Chizuko Kabuto Yutaka Higuchi Tomohiro Niimi Fumio Hamada Nobuhiko Iki Naoya Morohashi Sotaro Miyano 《Journal of inclusion phenomena and macrocyclic chemistry》2002,42(1-2):89-98
X-Ray crystal structures of the mono-, di-, and tri(p-tert-butyl)-substituted thiacalix[4]arenes (TC4As; 1, 2, and 3, respectively) have beendetermined. TC4As 1–3 adopt a cone conformation and form dimeric self-inclusion units in such a manner that phenol moieties are inserted into the cavity of each molecule. In all the crystal structures of 1–3, lateralface-to-face interactions exist between the phenol rings that do not bear a tert-butyl substituent, and seemingly, this molecular assembly stabilizes the formation of self-inclusion. TC4As 1 and 2 adopt a cone conformation with C2 symmetry, leading to the formation of rim-to-rim intermolecular hydrogenbonds so as to link the dimeric units up and down. On the other hand, 3 adopts a regular cone conformation with C4 symmetry to form cyclic hydrogen bonds withinthe rim part of TC4A. 相似文献