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991.
Masaaki Yoshifuji Manabu Shibata Kozo Toyota Ikuko Miyahara Ken Hirotsu 《Heteroatom Chemistry》1994,5(3):195-200
1-(2,4,6-Tri-t-butylphenyl)-1-phosphaallene reacted with dichlorocarbene to give 2-dichloromethylene-1-(2,4,6-tri-t-butylphenyl)-1-phosphirane. The structure was confirmed by X-ray crystal structure analysis. A similar isomerization product was obtained in the reaction of dichlorocarbene with 3-phenyl-1-(2,4,6-tri-t-butylphenyl)-1-phosphaallene. 相似文献
992.
993.
T Suzuki H Inagaki H Hamajima H Uesaka K Hori T Ikami 《Chemical & pharmaceutical bulletin》1999,47(6):880-883
Three metabolites of N-[2-(1-azabicyclo[3.3.0]octan-5-yl)ethyl]-2-nitroaniline fumarate (SK-946), a novel central muscarinic cholinergic receptor agonist, were prepared to confirm their proposed structures, and tested for muscarinic receptor affinity in vitro. 相似文献
994.
Kenzi Hori Nobuhisa Saitoh Shinjiro Kobayashi Tsugio Kitamura 《Theoretical chemistry accounts》1999,102(1-6):244-251
β, γ-Substituted γ-halo allylalkoxide ions decompose to form a halogen ion, formaldehyde, and an alkyne under mild conditions,
for example at room temperature. The E isomer does not differ from the Z isomer in terms of activation energy. We attempted
to shed light on the mechanism of the reaction by using ab initio molecular orbital calculations. The observed propensity
was confirmed by the present calculation on model molecules, γ-chloro allylalkoxide ions. We conducted further calculations
and compared the alkoxide results with a similar reaction of β-haloacrylate ions that release carbon dioxide instead of formaldehyde.
This similar reaction needs heating as high as 150°C. The activation energy of the acrylate ions (36–39 kcal mol−1) was calculated to be about 10 kcal mol−1 higher than that of the alkoxide ions. The activation energy of the E acrylate ion is smaller by 0.8 kcal mol−1 than that of the Z isomer at the MP2/6-31+G**//RHF/6-31+G* level of theory. This is consistent with experimental results.
While the ready deprotonation from the carboxylic group does not activate the acrylate ion very much, the alkoxide ion is
destabilized to a great degree in the process of anion formation. The difficulty in deprotonation that proceeds from the neutral
molecule is seen in the difference in the activation energies for the decomposition of the corresponding anions. Therefore,
the pK
a of a hydroxy or a carboxylic group plays the leading role in determining the magnitude of activation energies of allyl halides
with a negatively charged fragment.
Received: 2 July 1998 / Accepted: 9 September 1998 / Published online: 8 February 1999 相似文献
995.
C. Petrascu S. Bianco A.M. Bragadireanu F.L. Fabbri C. Guaraldo M. Iliescu T.M. Ito V. Lucherini M. Bregant E. Milotti A. Vacchi E. Zavattini M. Augsburger D. Chatellard P. Knowles F. Mulhauser L.A. Schaller L. Schellenberg H. Schneuwly J.-P. Egger D. Varidel W.H. Breunlich M. Cargnelli B. Gartner R. King B. Lauss J. Marton J. Zmeskal T. Ponta S.N. Nakamura T. Koike R.S. Hayano M. Hori T. Ishikawa T. Ishiwatari M. Iwasaki Y. Akaishi G. Beer A.C. Sanderson R. Seki 《Hyperfine Interactions》1999,118(1-4):53-57
The DEAR (DAΦNE Exotic Atom Research) experiment at the new φ-factory DAΦNE of Laboratori Nazionali di Frascati aims for a
1% measurement of the line shift of the K-complex due to strong interaction in kaonic hydrogen. This presentation is meant to prove that the high statistics and good
resolution obtainable with DEAR will be able to disentangle the kaonic hydrogen K-complex lines (a cascade unconstrained fit), obtaining in this way constraints for what concerns the cascade parameters and,
consequently, information regarding the physical processes involved in the kaonic hydrogen atomic cascade.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
996.
997.
Masako Nakagawa Manabu Ito Yuko Hasegawa Satoko Akashi Tohru Hino 《Tetrahedron letters》1984,25(35):3865-3868
We report the first total synthesis of (+)-tryptoquivaline 1a and of a key precursor, 2,3-dialkylquinazolinone 13b. 相似文献
998.
Egg-yolk phosphatidylcholine (EPC) and dipalmitoyl phosphatidylcholine (DPPC) were impregnated in a porous cellulose nitrate membrane, and permeabilities of oxygen, nitrogen, and carbon dioxide through these composite-type membranes were measured. Gases are suggested to permeate across the membrane by an activated flow of the solution—diffusion type through the impregnated lipid matrix. The EPC-filled membrane shows higher permeability and smaller activation energy of permeation compared to the DPPCfilled membrane, which is ascribed to the higher mobility of fatty acid chains of EPC compared to those of DPPC. 相似文献
999.
1000.
Kentaro Hori 《Communications in Mathematical Physics》1996,182(1):1-32
A study of the gauged Wess-Zumino-Witten models is given focusing on the effect of topologically non-trivial configurations
of gauge fields. A correlation function is expressed as an integral over a moduli space of holomorphic bundles with quasi-parabolic
structure. Two actions of the fundamental group of the gauge group is defined: One on the space of gauge invariant local fields
and the other on the moduli spaces. Applying these in the integral expression, we obtain a certain identity which relates
correlation functions for configurations of different topologies. It gives an important information on the topological sum
for the partition and correlation functions. 相似文献