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431.
Improved Negishi Cross‐Coupling Reactions of an Organozinc Reagent Derived from l‐Aspartic Acid with Monohalopyridines 下载免费PDF全文
Toyonobu Usuki Hiroto Yanuma Takahiro Hayashi Haruka Yamada Noriyuki Suzuki Yoshiro Masuyama 《Journal of heterocyclic chemistry》2014,51(1):269-273
The Negishi cross‐coupling reaction of an organozinc derivative prepared from protected l ‐aspartic acid with monohalopyridines was improved by employing a combination catalyst of Pd2(dba)3 and P(2‐furyl)3 and removing an extra Zn from the organozinc reagent via centrifugation. The reactivity of halogenated pyridines (Cl, Br, I) with substituents at the C2, C3, and C4 positions of the pyridine ring was investigated, and it was found that the use of 4‐iodopyridine as a substrate gave the best yield (90%) for the cross‐coupling reaction. 相似文献
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Sayaka Yoshiwaka Kosuke Sasagawa Keiichi Noguchi Noriyuki Yonezawa Akiko Okamoto 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(12):1096-1100
The title molecule, C40H32O6, possesses crystallographically imposed twofold symmetry, with the central two C atoms of the naphthalene unit sited on the rotation axis. The two 4‐phenoxybenzoyl groups in the molecule are twisted away from the attached naphthalene unit, with a torsion angle of 66.76 (15)° between the naphthalene unit and the carbonyl group (C—C—C=O), and are oriented in mutually opposing directions (anti orientation). There is an apparent difference in the conformations of the 4‐phenoxybenzoyl groups at the 1‐ and 8‐positions of the naphthalene ring between the title molecule and its methoxy‐bearing homologue [Hijikata et al. (2010). Acta Cryst. E 66 , o2902–o2903]. Whilst the 4‐phenoxybenzoyl groups in 2,7‐diisopropoxy‐1,8‐bis(4‐phenoxybenzoyl)naphthalene [Yoshiwaka et al. (2013). Acta Cryst. E 69 , o242] are situated in the same anti orientation as the title molecule, those of 2,7‐dimethoxy‐1,8‐bis(4‐phenoxybenzoyl)naphthalene are oriented in the same direction with respect to the naphthalene ring system, i.e. in a syn orientation. 相似文献
434.
Reactions of ruthenium complexes having 2-pyridinecarboxylato and 2,2'-bipyridine ligands with sodium azide in alcohol afforded nitrido-bridged diruthenium complexes, [{Ru(OR)(pyca)(bpy)}2(mu-N)](+) (R = CH3, C2H5). Diruthenium complexes showed diamagnetic properties, a linear Ru-N-Ru coordination configuration, and two irreversible oxidation waves and two reversible reduction waves. 相似文献
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438.
Kaori Hayashi Tominari Choshi Kyoko Chikaraishi Aimi Oda Rikako Yoshinaga Noriyuki Hatae Minoru Ishikura Satoshi Hibino 《Tetrahedron》2012,68(22):4274-4279
A new entry to the total synthesis of isocryptolepine (cryptosanguinolentine), isolated from Cryptolepis sanguinolenta, was achieved by constructing a tetracyclic ring system through a microwave-assisted tandem Curtius rearrangement and electrocyclic reaction of an aza 6π-electron system. The tetracyclic lactam was converted to isocryptolepine in a four-step sequence. 相似文献
439.
Keiji Fushimi Kota Anzai Shinji Tokuyama Yoshikazu Kiriiwa Noriyuki Matsumoto Atsushi Sekiya Daisuke Hashizume Kazuo Nagasawa Hirofumi Hirai Hirokazu Kawagishi 《Tetrahedron》2012,68(4):1262-1265
Five novel compounds (1–3, 5, and 6), and two known ones (4 and 7) were isolated from the culture broth of Agrocybe praecox. Their structures were determined by the interpretation of spectroscopic data. Compounds 1–4 inhibited hypocotyl growth of lettuce, and 1, 3, and 4 inhibited the root growth. 相似文献
440.
Kuwabara T Shiba K Nakajima H Ozawa M Miyajima N Hosoda M Kuramoto N Suzuki Y 《The journal of physical chemistry. A》2006,110(50):13521-13529
Three modified beta-cyclodextrins appended with a hydroxyazobenzene as a dye unit, 1, 2, and 3, each incorporating a different length spacer between the beta-CD and the dye unit with a bis(propyl(oxyethylene)), butylene, and amide bond spacer, respectively, were synthesized in order to investigate their spectroscopic changes induced by pH and host-guest complexation as well as to investigate their conformations and guest-binding properties by means of absorption and induced circular dichroism spectroscopies in aqueous solutions. All hosts accommodated the dye unit in their own CD cavities with an orientation parallel to the CD axis, forming intramolecular complexes. When the pH of the solution changed, the structure changed in response to pH without conformational changes. Existing as the phenol form under acidic condition, they were converted to the yellow phenolate form by dissociation of a proton of the hydroxyl group in the dye unit with increasing pH (pK(a1); 7.62 for 1, 7.44 for 2, 8.00 for 3). Further increase in pH led to the dissociation of the ammonium proton in the secondary amine group in the spacer of 1 and 2 (pK(a2); 8.76 for 1, 8.67 for 2). Upon addition of 1-adamantanol (AN) as a guest, all hosts accommodated AN in their CD cavities, forming 1:1 host-guest inclusion complexes. The complexation phenomena were accompanied with changes in the conformation of the hosts, in which the dye units of 1 and 2 are excluded to outside of the cavity, but not for 3. The dye unit of 3 remained in the cavity, where the guest was also included partly. Therefore, the guest-binding abilities of 1 and 2 were larger than that of 3, which has poor binding ability. The binding constants of 1, 2, and 3 for AN are estimated to be 7400, 1940, and 140 M(-1) at pH 3.2, respectively. However, the guest-binding abilities of 1 and 2 were dependent on the pH of the solution. The ability of 1 under weak alkaline condition was stronger than under acidic or alkaline conditions, while that of 2 increased with increasing pH. Under the condition from neutral to weak alkaline media, 1 and 2 demonstrated color changes from colorless to yellow upon formation of inclusion complexes. When 1-adamantanecarboxylic acid (AC) was used as the charged guest, 1 and 2 bound to AC with a larger binding constant than AN. On the other hand, 1 and 2 bound to 1-adamantineamine (AA) with a smaller binding constant than AN. All these results demonstrate that the complexation phenomena depend on the pH of the solution as well as the length of the spacer of the hosts and that the electrostatic interaction between the host and the guest is also important for forming a stable complex. 相似文献