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141.
142.
Tomoya Fujiwara Kazuki Hashimoto Masanori Umeda Saki Murayama Yuki Ohno Bo Liu Hisanori Nambu Takayuki Yakura 《Tetrahedron》2018,74(35):4578-4591
The divergent synthesis of penaresidin B and its straight side chain analogue was accomplished by constructing an azetidine ring via SN2 type cyclization of protected 2,3-syn-3,4-syn-4-amino-1,3-dihydroxyhept-6-en-2-yl mesylate and late-stage introduction of an alkyl side chain via olefin cross-metathesis of 4-allylazetidine with readily available terminal alkenes. This synthetic route would be useful to synthesize penaresidin side chain analogues. 相似文献
143.
Rui Umeda 《Journal of organometallic chemistry》2011,696(9):1916-1919
The first example of the FBW rearrangement using of lanthanum metal and a catalytic amount of iodine was disclosed. When gem-diiodo- and gem-dibromoalkenes were treated with lanthanum metal in the presence of a catalytic amount of iodine, the reductive dehalogenation of these compounds smoothly proceeded to produce the corresponding alkynes in moderate to good yields. 相似文献
144.
145.
A miniaturized FIA system for the determination of residual chlorine in environmental water samples.
Jiye Jin Yasutada Suzuki Naoyoshi Ishikawa Toyohide Takeuchi 《Analytical sciences》2004,20(1):205-207
The present study was aimed at developing a portable miniaturized FIA system with a two-electrode based amperometric detector for on-site monitoring of residual chlorine in environmental samples. The electrode potential control and current data collection were conducted with a home-designed potentiostat with a size of 150 x 100 x 40 mm and the weight of 350 g. It was confirmed that the amperometric response increased in proportion to the chlorine concentration up to 5 microg/ml, and the detection limit for chlorine was 0.05 microg/ml. Besides a drastic reduction in the size of the analytical system, such miniaturization achieved the advantages of increased speed, minimal mobile-phase consumption, and high sensitivity. The proposed method was successfully applied to the determination of residual chlorine in samples of pool water and tap water. The results were well agreed with those obtained by the N,N-diethyl-p-phenylenediamine (DPD) photometric method. 相似文献
146.
A method for a beam shaping optics is proposed to convert a laser beam profile into arbitrary required intensity distribution.
Surface profile of the beam shaping optics is designed by using Snell's law to convert the required intensity distribution
at the beam irradiation plane from the input intensity distribution. A computerized numerical control (CNC) lathe is employed
to fabricate the beam shaping optics, and acrylic resin is used for the material. The acrylic resin plate is cut by a ball
type of grinding wheel tool consisted on diamond powder and polished by a cone type felt buff with alumina ceramics powder.
The CNC lathe is powerful tool to control the position of these tools. The fabricated beam shaping optics is aspheric shape
with 4 mm of thickness and it works to convert the intensity distribution of multi-mode beam profile with 13 mm of diameter
into a flat top cylinder with 1 mm of diameter. A working distance of the beam shaping optics is 60 mm, and its transmittance
is over 98%. It succeeds to fabricate uniform melting mark of 0.6 mm diameter on a steel target by the YAG laser process. 相似文献
147.
148.
Jukiya Sakamoto Yuhei Umeda Kenta Rakumitsu Michinori Sumimoto Hayato Ishikawa 《Angewandte Chemie (International ed. in English)》2020,59(32):13414-13422
A collective synthesis of glycosylated monoterpenoid indole alkaloids is reported. A highly diastereoselective Pictet–Spengler reaction with α‐cyanotryptamine and secologanin tetraacetate as substrates, followed by a reductive decyanation reaction, was developed for the synthesis of (?)‐strictosidine, which is an important intermediate in biosynthesis. This two‐step chemical method was established as an alternative to the biosynthetically employed strictosidine synthase. Furthermore, after carrying out chemical and computational studies, a transition state for induction of diastereoselectivity in our newly discovered Pictet–Spengler reaction is proposed. Having achieved the first enantioselective total synthesis of (?)‐strictosidine in just 10 steps, subsequent bioinspired transformations resulted in the concise total syntheses of (?)‐strictosamide, (?)‐neonaucleoside A, (?)‐cymoside, and (?)‐3α‐dihydrocadambine. 相似文献
149.
150.
K Yagi T Seto M Terakado F Umeda T Doi T Imanishi Y Miura 《Chemical & pharmaceutical bulletin》1992,40(12):3292-3296
The nucleotide sequences of membrane-bound hydrogenase small (hupS) and large (hupL) subunit genes of hydrogen bacterium Alcaligenes hydrogenophilus were determined. The hupS and hupL genes encoded polypeptides of 363 and 619 amino acids, respectively. The hupS was located upstream of hupL with 35bp of intergenic region. The consensus ribosome-binding sequences were identified upstream of the start codons of hupS and hupL. Amino acid sequence of hupS is very similar to that of Rhodobacter capsulatus, Bradyrhizobium japonicum, and Azotobacter vinelandii at amino acid levels of 82%, 77%, and 81%, respectively. Similarly, amino acid sequence of HupL is similar to that of R. capsulatus, B. japonicum, and A. vinelandii at amino acid levels of 63%, 65%, and 68%, respectively. Northern hybridization analysis showed that hupS and hupL were co-transcribed, and addition of fructose to the culture medium remarkably decreased the amount of mRNA transcribed from hupS and hupL. 相似文献