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141.
Masahiko Seki Mayumi KimuraMasanori Hatsuda Shin-ichi YoshidaToshiaki Shimizu 《Tetrahedron letters》2003,44(49):8905-8907
2-Thiazolidinone derivatives were shown to be novel protective surrogates of a thiol group in l-cysteine derivatives. After elaboration at the C-4 substituent, the thiol group was completely liberated by simple heating in DMF whose atom efficiency is 100%. A practical synthesis of (+)-biotin was accomplished by the use of the strategy employing 4-functionalized 2-thiazolidinone derivatives as the intermediates, allowing a synthesis of (+)-biotin in 10 steps and in 31% overall yield. Short steps, high yield, and ease of operation of the present approach would permit the hitherto most efficient access to (+)-biotin. 相似文献
142.
Motomasa Kobayashi Tohru Yasuzawa Yuji Kobayashi Yoshimasa Kyogoku Isao Kitagawa 《Tetrahedron letters》1981,22(44):4445-4448
A novel diterpenoid acetate named alcyonolide has been isolated from an Okinawan soft coral of the genus and the absolute stereostructure has been assigned on the basis of chemical and physicochemical evidence. 相似文献
143.
Isao Kitagawa Motomasa Kobayashi Tohru Yasuzawa Byeng Wha Son Minoru Yoshihara Yoshimasa Kyogoku 《Tetrahedron》1985,41(6):995-1005
Four new anti-tumor active prostanoids, named claviridenone-a (3), claviridenone-b (4). claviridenone-c (5), and claviridenone-d (6), as well as 20-acetoxy-claviridenone-b (7) and 20-acetoxy-claviridenone-c (8), have been isolated from the Okinawan soft coral (stolonifer) Clavularia viridis Quoy and Gaimard (Stolonifera, Clavulariidae). The absolute stereostructures of these six prostanoids have been elucidated on the basis of chemical and physicochemical evidence which includes the application of the CD exciton chirality method to their various benzoyl derivatives having benzoate and conjugated diene chromophores. Claviridenones possess a characteristic cross-conjugated dienone-enone chromophore. 相似文献
144.
145.
Masakatsu Shibasaki Mayumi Yamazaki Katsuhiko Iseki Shiro Ikegami 《Tetrahedron letters》1982,23(50):5311-5314
A chirally directed total synthesis of (+)-hirsutic acid from 1,3-cyclooctadiene has been accomplished in a highly stereocontrolled manner. 相似文献
146.
Syntheses of 15N-enriched polyamines 总被引:1,自引:0,他引:1
K Samejima Y Takeda M Kawase M Okada Y Kyogoku 《Chemical & pharmaceutical bulletin》1984,32(9):3428-3435
147.
Mayumi Hojo 《Numerical Functional Analysis & Optimization》2016,37(5):541-553
In this article, we consider the split common null point problem in Banach spaces. Then, using the shrinking projection method, we prove a strong convergence theorem for finding a solution of the split common null point problem in Banach spaces. It appears that such a theorem is a first in Banach spaces. 相似文献
148.
Facile H2 heterolysis was found to be mediated by coordinatively unsaturated Cp*Ir and Cp*Rh thiolate complexes. The reaction of iridium complex is reversible, and the formation of an intermediary Ir-H/thiol complex was detected. The reversible conversion between thiolate complex+H2 and hydride complex+thiol provides an intriguing functional model of [NiFe] hydrogenase. 相似文献
149.
A building unit of Prussian blue was isolated as a cyanide-bridged iron cube of [Fe(II)4Fe(III)4(CN)12(tp)8] x 12 DMF x 2 Et2O x 4 H2O [tp(-) = hydrotris(pyrazolyl)borate]. A cyclic voltammogram showed quasi-reversible four-stepped redox waves, which correspond to [Fe(III)4Fe(II)4]/[Fe(III)5Fe(II)3](+), [Fe(III)5Fe(II)3](+)/[Fe(III)6Fe(II)2](2+), [Fe(III)6Fe(II)2](2+)/[Fe(III)7Fe(II)1](3+), and [Fe(III)7Fe(II)1](3+)/[Fe(III)8](4+) processes. Controlled potential absorption spectral measurements revealed two intervalence charge-transfer bands at 816 and 1000 nm, which were assigned to charge transfers from Fe(II) ions to adjacent and remote Fe(III) ions, respectively, in the cube. 相似文献
150.
Sakai D Matsuda Y Hachiya M Mori M Fujii A Mikami N 《The journal of physical chemistry. A》2008,112(30):6840-6849
Vibrational spectroscopy of size-selected formamide-water clusters, FA-(H2O)n , n = 1-4, prepared in a supersonic jet is performed with vacuum-ultraviolet-ionization detected-infrared predissociation spectroscopy (VUV-ID-IRPDS). The cluster structures are determined through comparisons of the observed IR spectra with theoretical calculations at the MP2/6-31++G** level. The FA-(H2O)n , n = 1-3, clusters have ring-type structures, where water molecules act as both single donor and single acceptor in the hydrogen-bond network between the amino and carbonyl groups of FA. For FA-(H2O)4, on the other hand, the absence of the free NH stretching vibration indicates formation of a double ring type structure, where two NH bonds of the amino group and the carbonyl oxygen of FA form hydrogen bonds with water molecules. An infrared spectrum of the formamide-water cluster cation, [FA-H2O](+), is also observed with infrared predissociation spectroscopy of vacuum-ultraviolet-pumped ion (IRPDS-VUV-PI). No band is observed for the free OH stretches of neutral water. This shows [FA-H2O](+) has such a structure that one of the hydrogen atoms of the water moiety is transferred to the carbonyl oxygen of FA(+). 相似文献