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61.
Ayabe M Ikeda A Shinkai S Sakamoto S Yamaguchi K 《Chemical communications (Cambridge, England)》2002,(10):1032-1033
Porphyrin dimer 1, which does not have an inside cavity and cannot interact with [60]fullerene (C60), becomes an excellent C60-acceptor with a large cavity in the presence of a Pd(II) complex. 相似文献
62.
[reaction: see text]. Rhodium complex-catalyzed carbonylative alkene-alkyne coupling proceeds using aldehydes as a CO source. Cinnamaldehyde is the best CO donor, and various cyclopentenones were provided in high isolated yields by a solvent-free system. 相似文献
63.
A variety of jumps has in the past been identified in diffusion of atoms on 1D channeled surfaces. To establish the jump processes important in diffusion on a 2D surface, the movement of individual Pd atoms has been examined on W(110). From the distribution of displacements of Pd at high temperatures, double jumps are found along the close-packed <111>. For the first time, sizable differences are also observed between the mean-square displacements along x and y, which demonstrate unexpected contributions from jumps along <110>, but not along <001>. These jumps proceed over activation barriers higher than for single jumps, under conditions predicted from previous work with Pd on the channeled W(211). 相似文献
64.
π, π*-Induced Photocleavage of γ, δ-Epoxy-eucarvone . On 1π, π*-excitation 1 undergoes cleavage of the C, C-oxirane bond ( 1 → c ) and isomerizes to the bicyclic dihydrofurane compound 5 . In addition, 1 shows photocleavage of the C (γ), O-oxirane bond ( 1 → d ) and gives the isomers 2, 3, 6, 7 and 8. Furthermore, the cyclohexenone 9 and the cyclohexene-1, 4-dione 10 are formed presumably via an intermediate 13 , which could also arise from d. Besides these products the compounds 11 and 12 are obtained, which are photoproducts of 2 . 相似文献
65.
Shibata T Fujimoto T Yokota K Takagi K 《Journal of the American Chemical Society》2004,126(27):8382-8383
An asymmetric [2+2+2] cycloaddition of an alpha,omega-diyne, possessing ortho-substituted aryl groups on its terminus, and a monoalkyne with oxygen functionalities gave various axially chiral teraryl compounds. The coupling proceeded with extremely high enantio- (>99.5% ee) and diastereoselectivities (dl/meso = >95/5) when catalyzed by an iridium-chiral phosphine complex. As the products were readily transformed into diol compounds by deprotection without racemization, the present procedure provides access to a new chiral pool of diol compounds with C2 symmetry. 相似文献
66.
Takada K Uehara T Nakao Y Matsunaga S van Soest RW Fusetani N 《Journal of the American Chemical Society》2004,126(1):187-193
Three new alpha-glucosidase inhibitors, schulzeines A-C (1-3), were isolated from the marine sponge Penares schulzei. Their structures were elucidated by spectral analysis and chemical degradations to be the isoquinoline alkaloids, encompassing two amino acids, and C(28) fatty acid, the last of which was sulfated. Absolute stereochemistry of schulzeines was determined by application of the modified Mosher analysis to fragments obtained by chemical degradation. Schulzeines A-C inhibit alpha-glucosidase with IC(50) values of 48-170 nM. 相似文献
67.
Chiba JY Tanaka K Ohshiro Y Miyake R Hiraoka S Shiro M Shionoya M 《The Journal of organic chemistry》2003,68(2):331-338
This paper describes a convenient synthetic procedure for nucleoside mimics, 1-6, in which the 3',5'-hydroxy groups of natural 2'-deoxythymidine or 2'-deoxyadenosine are replaced by thiol, amine, or alkylthiol groups. Such nucleosides would be built up into a single DNA strand with cooperative participation of metal coordination, where internucleoside linkages are replaced by metal complexation motifs. The X-ray crystal structure and complexation behaviors of 3',5'-dithiothymidine, 1, with Au(I) are also reported. 相似文献
68.
Hori A Kataoka H Okano T Sakamoto S Yamaguchi K Fujita M 《Chemical communications (Cambridge, England)》2003,(2):182-183
The reversible cross-catenation of two different coordination rings (Pd(II)- and Pt(II)-linked rings) has been achieved by using the labile nature of the Pd-N interaction and efficient hydrophobic contact between the rings. 相似文献
69.
Takayama H Katakawa K Kitajima M Yamaguchi K Aimi N 《Chemical & pharmaceutical bulletin》2003,51(10):1163-1169
Ten new alkaloids, lycoposerramines-F (1), -G (2), -H (3), -I (4), -J (5), -K (6), -L (7), -M (8), -N (9), and -O (10), having lycopodine-related structures, were isolated from the club moss Lycopodium serratum THUNB. and their structures were elucidated on the basis of spectroscopic analysis and/or chemical transformation. 相似文献
70.
Yamasaki R Tanatani A Azumaya I Saito S Yamaguchi K Kagechika H 《Organic letters》2003,5(8):1265-1267
[reaction: see text] Introduction of an electron-withdrawing group on the aromatic ring of N-methylacetanilide decreased the ratio of the cis conformer, and the ratio correlates well with the Hammett sigma values of the substituents. These steric properties can be applied to achieve amide conformational switching by protonation at the aromatic substituent of 4-[bis(dimethylamino)]-N-methylacetanilide or N-[p-(dimethylamino)phenyl]-N-phenylacetamide. 相似文献