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21.
One-dimensional potential energy curves for the isomerization of protonated Schiff base of retinal (PSBR) in bacteriorhodopsin (bR), i.e., isomerization from all-trans- to 13-cis-forms, have been calculated by means of time-dependent density functional theory (TD-DFT) calculations, in order to elucidate the mechanism of initial step in photo-absorption. The transition state of the isomerization in the first excited state is located at theta(13-14)=58 degrees , where theta(13-14) means twist angle around the C(13)=C(14) double bond of PSBR The potential barrier is formed by the avoided crossing between S(1) (B(u)-like) and S(2) (A(g)-like) states. The mechanism of the isomerization was discussed on the basis of theoretical results. 相似文献
22.
Electrolytic coupling reaction of laudanosine (1) gave the O-methylflavinantine (II). N-Ethoxycarbonylated dihydrostilbene (IVa) gave a rearranged dienone (Va) and N-trifluoro-acetylated dihydrostilbene (IVb) contrastively gave an unrearranged dienone (Vb). 相似文献
23.
Taichiro Kugo Tetsuji Kuramoto Shozo Uehara 《Zeitschrift fur Physik C Particles and Fields》1983,19(3):241-250
It is investigated to what extent the well-known algebra \(\left\{ {Q^S ,\bar Q^S } \right\} = \gamma ^\mu P_\mu \) in the rigid supersymmetry theory holds in quantum supergravity: The anti-commutator \(\left\{ {Q_\alpha ^S ,\bar Q_\beta ^S } \right\} = \gamma ^m \tilde P_m \) defines an “internal” translation generator \(\tilde P_m \) , quite another from the “external” translation generatorP μ. It is, however, shown that those two operators give the same matrix elements between any two physical states aside from a proportional factor. Such a “miracle” is caused by some particular properties of global gauge transformation charge universal in gauge theories. These properties are fully clarified in a general manner. 相似文献
24.
Tetsuji Kametani Hiroko Kasai Etsuko Sato Toshio Suzuki 《Journal of Chemical Sciences》1988,100(2-3):91-111
For the purpose of organic syntheses of some corynanthe-type indole alkaloids, sesquiterpenes, and steroids, optically active
intermediates cyclopentanone 3-allylalcohol, α-methylene-γ-butylo lactones andtrans-hydrindanone-propionic acid, were synthesized from (R)- and (S)-isopropylideneglyceraldehyde derived fromD-mannitol andLascorbic acid, respectively, utilizing Claisen rearrangement as a key reaction. Actually total syntheses of natural alkaloids,
(-)-antirhine, (+)-dihydroantirhine and (-) dihydrocorynantheol were accomplished. 相似文献
25.
Abstract— Effects of extracellular Ca2+ concentration and papaverine on the PIII response of the electroretinogram and the dark adaptation process of the visual cells were studied in the isolated, aspartate-treated bullfrog retina. The amplitudes of both the fast and slow PIII responses are increased in 0.01 m M Ca2+ solution, but decreased in Ca2+ -free solution containing 1 m M EDTA. The application of 0.1 m M papaverine in the presence of 1 m M Ca2+ led to the enhancement of the slow PIII response at lower stimulus intensity and the prolongation of the slow PIII response, but these effects of papaverine on the response were lost when Ca2+ was removed from the bathing fluid. The half-time of recovery of the fast PIII response amplitude after switching off the adapting light was a linear function of the amount of bleached rhodopsin. Papaverine in the absence of Ca2+ produced about 2-fold increase in the half-time of recovery of the response. These findings suggest that chemical reactions which are sensitive to papaverine in the absence of Ca2+ are implicated in the dark adaptation process of the visual cells. 相似文献
26.
Tetsuji Kametani Kazuo Kigasawa Mineharu Hüragi Nagatoshi Wagatsuma Setsu Saitoh Hideo Sugi 《Journal of heterocyclic chemistry》1973,10(3):313-315
Acid treatment of the alkylated products of (Va, Vb, and VIII) of piperidinols IVa and IVb, and tetrahydropyridine VII with β-bromoethylbenzene, afforded 1,2,3,4,5,6-hexahydro-8-hydroxy-2,6-methano-6,1 1-dimethyl-3-phenethyl-3-benzazocine (la) in good yield. Piperidinols Va and Vb were also obtained from the reaction of N-(3-methyl-3-pentenyl)-β-phenethylamine (IIb) with methyl 3-(4-methoxyphenyl)-2,3-epoxypropionate. 相似文献
27.
A stereoselectivity in an intramolecular cycloaddition of the olefinic -quinodimethanes 13 and 23 generated from the thermolysis of optically active 4β-[2-(4-methoxybenzocyclobutenyl)ethyl] -5α-methoxymethyl-3-phenyl-thio-methylenefuran-2-ones 12 and 22, respectively, is studied and a stereoselective synthesis of (+)--4,5-( 4-methoxybenzo) -1β,7aβ-(2α-methoxymethyl-5-oxofuro)hydrindane 1 is also described. 相似文献
28.
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30.
Venkataprasad Jalli Suvratha Krishnamurthy Hiroyoshi Kawasaki Tetsuji Moriguchi Akihiko Tsuge 《合成通讯》2013,43(19):2216-2226
An efficient and facile method for the synthesis of novel spiro[indole-2,2′-pyrroles] from N-methyl-3-isatin imines, t-butyl isocyanide, and dialkyl acetylenedicarboxylate has been achieved by [3 + 2] cyclo addition reaction. All the products were purified by column chromatography as yellow solids and confirmed with 1H NMR, 13C NMR, fast atom bombardment, mass, and infrared. Compound 11 was further confirmed with x-ray analysis. 相似文献