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201.
Tertiary amides, ureas, and amines undergo direct intermolecular addition to aldehydes under the Et3B/air conditions, thereby providing a unique and simple means for the radical sp3 C-H transformation of nitrogen-containing molecules. 相似文献
202.
From the fresh roots of Solanum abutiloides, four new 26-aminocholesteryl glycosides were obtained, and their structures were characterized by analysis of their spectra data, including two-dimensional (2D) NMR spectroscopy. These compounds were regarded as key intermediates in the biogenesis of steroidal alkaloids. 相似文献
203.
Liu JG Naruta Y Tani F Chishiro T Tachi Y 《Chemical communications (Cambridge, England)》2004,(1):120-121
A binucleating porphyrin with covalently appended copper chelates having a cross-linked imidazole-phenol group as the novel active site model of cytochrome c oxidase has been prepared, and the dioxygen adduct of its iron(II)-copper(I) complex was spectroscopically characterized. 相似文献
204.
Yoshimitsu Nagao Takashi Honjo Satoru Goto Motoo Shiro Yoshihisa Sei 《Tetrahedron letters》2004,45(47):8757-8761
The dimeric crystalline structure of acetazolamide 1 and thiadiazolinethione 2 bearing intramolecular nonbonded S?O interactions, in each different hydrogen-bonding manner was clarified by their X-ray crystallographic analysis. Existence of the dimeric structure of 1 and 2 in a MeOH solution could be suggested on the basis of their cold-spray ionization mass spectrometry. The intramolecular nonbonded S?O interaction was precisely recognized in the complex crystalline structures of carbonic anhydrase I inhibitor 1 and stromelysin inhibitors 2-4 with each specific enzyme. The computational evaluation of the possible monomeric seven conformers of 1 and two model compounds 5 and 6 of 2-4 based on DFT calculations defined that the conformer bearing the intramolecular nonbonded S?O interaction is most stable. 相似文献
205.
Cyclodextrin-enclosed substances of Brazilian propolis 总被引:1,自引:0,他引:1
Nafady AM El-Shanawany MA Mohamed MH Hassanean HA Nohara T Yoshimitsu H Ono M Sugimoto H Doi S Sasaki K Kuroda H 《Chemical & pharmaceutical bulletin》2003,51(8):984-985
By using beta-cyclodextrin-inclusion as a unique technique, an efficient separation of pharmacologically active phenolic compounds from Brazilian propolis was achieved to provide one new compound, 3-(3-hydroxy-3-methyl-butyl)-5-prenyl-4-hydroxycinnamic acid, together with two common cinnamic acid derivatives, artepillin C and capillartemisin A, and two known flavanols, aromadendrin and 3,5,7-trihydroxy-4'-methoxyflavanol. 相似文献
206.
207.
γ-Keto-sulfoxides have been very conveniently synthesized through a series of reactions from commercially available acrolein. They were obtained as crystals and shown to be effective as the vinyl ketone equivalents. 相似文献
208.
209.
Three new 15,16-seco-cycloartane glycosides, which were constructed by a C-C bond cleavage in the D ring, have been isolated from Cimicifuga Rhizome for the first time. Their structures were determined by the use of 2D NMR techniques and chemical evidence. 相似文献
210.
Kiyota N Shingu K Yamaguchi K Yoshitake Y Harano K Yoshimitsu H Ikeda T Nohara T 《Chemical & pharmaceutical bulletin》2007,55(1):34-36
Three new C(28) steroidal glycosides, isotubocaposides A (1), B (2), and C (3), were isolated from the fruits of Tubocapsicum anomalum MAKINO. Their chemical structures were elucidated on the basis of spectroscopic and X-ray diffraction analysis of p-bromobenzoyl derivative (5) of isotubocaposigenin (4), the sapogenol derivative of these three glycosides. Isotubocaposides have the structural peculiarity of an unusual side chain carrying a C-21 bound to C-24 on the lactone ring. 相似文献