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971.
Sato K Tamura M Tamoto K Omote M Ando A Kumadaki I 《Chemical & pharmaceutical bulletin》2000,48(7):1023-1025
We have reported that the reaction of ethyl bromodifluoroacetate (1) with alkenyl iodides in the presence of copper powder gives ethyl alkenyldifluoroacetates. As an extension of this reaction, reaction of 1 with Michael acceptors in the presence of copper powder was examined and found to give 1,4-addition products selectively, unless the acceptor has a group stabilizing a radical intermediate, such as a phenyl group. 相似文献
972.
Treatment of alkyl chrysanthemate with Lewis acid leads to C3 epimerization, while protonic acid treatment gives rise to selective C2C3 bond cleavage. The latter method is successfully applied to the synthesis of optically active tetrahydrolavandulol. 相似文献
973.
The discovery that lithium bis(trifluoromethane)sulfonamide (LiTFSI)/1‐nitropropane (PrNO2) solution functions as a less polar alternative to lithium perchlorate (LiClO4)/nitromethane (MeNO2) solution has led to the development of a novel thermomorphic system for electrocatalytic Diels‐Alder reactions. Methyl cyclohexane (Me‐c‐Hex) can form a monophasic condition with LiTFSI/PrNO2 solution at room temperature, enabling the use of hydrophobic dienophiles. After the electrochemical reaction, a biphasic condition can be formed at –50°C, where the cycloadducts are selectively recovered from the upper Me‐c‐Hex phase and the remaining lower LiTFSI/PrNO2 solution can be reused. 相似文献
974.
Hideaki Bando Keiji Tamura Ryuichi Shimizu Masahiko Inoue 《Surface and interface analysis : SIA》2007,39(1):9-15
A Monte Carlo (MC) simulation program written in C++ has been newly developed to describe the dynamic processes of depth profiling with low energy ions. This MC simulation was applied to the depth profiling of GaAs/AlAs reference material for Ne+, Ar+, and Xe+ ions to elucidate the depth resolution attained by surface analytical techniques. The result clearly predicts that there is a considerable difference between the depth resolutions estimated from the leading and trailing edges of Ne+ and Xe+ ions, whereas the difference is quite small for Ar+ ions. Systematic investigation of the dependence of theoretical depth resolution on primary ion energy has revealed that the preferential sputtering primarily caused by the difference in energy transfer to target atoms through elastic collisions between incident ions and target atoms results in the difference between the leading and trailing edges. The inclusion of other factors, e.g. preferential sputtering effect caused by the metallization of Al atoms on the topmost surface, etc. for further improvement of the MC simulation modeling before accommodating quantitative arguments on the depth resolution is strongly recommended. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
975.
Tumor promoters such as phorbol esters bind strongly to protein kinase C (PKC) isozymes to induce their activation. Since each PKC isozyme is involved in diverse biological events in addition to tumor promotion, the isozymes serve as promising therapeutic targets. Tumor promoters bind to the C1A and/or C1B domain of conventional (alpha, betaI, betaII, and gamma) and novel PKC isozymes (delta, epsilon, eta, and theta). As these C1 domains play differential roles in PKC activation and their translocation in cells, the development of agents with binding selectivity for individual C1 domains is a pressing need. For this purpose, we established a synthetic C1 peptide library of all PKC isozymes. The library enabled us to identify indolactam-V (1) as a promising lead compound. Our diverse structure-activity studies on 1 indicated that the position of the hydrophobic substituent on the indole ring dominates the PKC isozyme- and C1 domain-selective binding rather than conformation of the nine-membered lactam. Moreover, we suggested that the indole ring of 1 could be involved in the CH/pi interaction with Pro-11 of the C1B domain of PKCdelta. This invaluable information will lead to the structural optimization of the PKCdelta ligand as exemplified by the design and synthesis of naphtholactam-V8 (21). 相似文献
976.
The first syntheses of (-)-funebrine [(-)-1] and (-)-funebral [(-)-2] are described. The syntheses feature sequential formation of nitrone VI from methyl glyoxylate (5) with oxime 6, transesterification of nitrone VI with (E)-crotyl alcohol (4), and intramolecular cycloaddition of the resulting nitrone VII bearing crotyl ester to afford cycloadduct 7 as a major product. The adduct 7 was readily elaborated to amino lactone (-)-3, the key synthetic intermediate of (-)-1 and (-)-2. 相似文献
977.
Toshikazu Takata Kimie Hoshino Eriko Takeuchi Yoshiharu Tamura Wataru Ando 《Tetrahedron letters》1984,25(42):4767-4770
In the photooxidation of 3-acyl-2,2-dimethyl-4(R)-substituted thiazolidine derivatives, 5(R)-hydroxy derivative obtained was found to be derived from the 5-hydroperoxy derivative which was isolated and characterized. 相似文献
978.
Jakob Wirz Gabriele Persy Erika Rommel Ichiro Murata Kazuhiro Naksuji 《Helvetica chimica acta》1984,67(1):305-317
The title compound 1b ideally meets the theoretical requirements for the occurrence of an adiabatic photoisomerization in the lowest excited state (1 1b *) and, indeed, the predominant primary photoreaction observed is the conversion to its fluorescent valence isomer 10b, 10c-methano-cis-10b 10c-dihydropyrene (1 1a *). The mechanism for the formation often previously observed photoproduct 8b, 9a-dihydro-9H - cyclopropa[e]pyrene ( 4a ) has been analyzed in some detail (Scheme). Below ? 30°C the reaction path consists of a three quantum process (two di-π-methane rearrangements and photochemical 1,7-H shift) involving two thermally stable, but light-sensitive isomers 8,11b-methanocyclodeca[cde]naphthalene ( 2b ) and 9H -cyclohepta[def]-phenanthrene ( 3b ). At room temperature the rearrangement 2b→4a proceeds with a single excitation step bypassing the ground state intermediate 3b . Finally, upon prolonged irradiation of ( 4a ), the methylene group is lost to yield pyrene. Compound 2b completes the series of all possible adducts of methylene to a C?C bond of pyrene. 相似文献
979.
Yasumitsu Tamura Hironori Hayashi Yoshiro Nishimura Masazumi Ikeda 《Journal of heterocyclic chemistry》1975,12(2):225-230
1-Alkyl-3-aminobenzimidazolium salts react with dimethyl acetylenedicarboxylate or dibenzoylacelylene in the presence of base to produce unusual 1:1 adducts, 1-(2′-alkylaminophenyl)-pyrazole derivatives. Treatment of the 3-amino salts with benzaldehyde in the presence of alkali gives benzaldehyde 2-(N,N-acylalkylamino)phenylhydrazones. The same hydrazones are obtained by alkaline treatment of 1 -alkyl-3-benzaliminobenzimidazolium salts, which are prepared from the 3-amino salts and benzaldehyde. 相似文献
980.
Kazuhiro Matsumoto 《Tetrahedron letters》2004,45(11):2385-2388
Pentagonal bipyramidal Hf(salen) complex 1 was found to serve as a catalyst for 1,4-addition reaction of thiol to N-(2-alkenoyl)-2-oxazolidinones. 相似文献