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141.
In order to obtain a highly concentrated, pure and super-hot [gamma-32P]ATP, we improved the purification method of super-hot [gamma-32P]ATP which was synthesized by the method of Johnson and Walseth (1979). The super-hot [gamma-32P]ATP was synthesized in a relatively large volume (2 ml) of reaction mixture and purified using semi-micro scale anion exchange chromatography (Dowex 1 X 2, 60-70 microliters column volume). In combination with washing the reaction product with certain organic solvents, this chromatography technique makes it possible to obtain a highly concentrated and pure super-hot [gamma-32P]ATP (approx. 7,000 Ci/mmol; 20-30 mCi/ml) from [32P]Pi of any commercial source in a good yield. 相似文献
142.
Copper(II) is determined by non-extractive spectrophotometry as a complex of butylene dithiocarbamate formed in situ by reaction between carbon disulfide and pyrrolidine in aqueous Triton X-100 medium. This method is similar to that with butylene dithiocarbamate as starting material in the sense of simplicity, sensitivity, precision and accuracy. Pyrrolidine is the best of seven secondary amines tested in this way for copper determinations. 相似文献
143.
Dr. Yu Harabuchi Dr. Hiroki Hayashi Dr. Hideaki Takano Prof. Tsuyoshi Mita Prof. Satoshi Maeda 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2023,135(1):e202211936
Systematic reaction path exploration revealed the entire mechanism of Knowles's light-promoted catalytic intramolecular hydroamination. Bond formation/cleavage competes with single electron transfer (SET) between the catalyst and substrate. These processes are described by adiabatic processes through transition states in an electronic state and non-radiative transitions through the seam of crossings (SX) between different electronic states. This study determined the energetically favorable SET path by introducing a practical computational model representing SET as non-adiabatic transitions via SXs between substrate's potential energy surfaces for different charge states adjusted based on the catalyst's redox potential. Calculations showed that the reduction and proton shuttle process proceeded concertedly. Also, the relative importance of SET paths (giving the product and leading back to the reactant) varies depending on the catalyst's redox potential, affecting the yield. 相似文献
144.
Yujiro Hayashi 《Chemical record (New York, N.Y.)》2023,23(7):e202200159
The aldol reaction is one of the most important carbon-carbon bond-forming reactions in organic chemistry. Asymmetric direct cross-aldol reaction of two different aldehydes has been regarded as a difficult reaction because of the side reactions such as self-aldol reaction and over reaction. We found that trifluoromethyl-substituted diarylprolinol, α,α-bis[3,5-bis(trifluoromethyl)phenyl]-2-pyrrolidinemethanol ( 1 ), is an effective organocatalyst that promotes several cross-aldol reactions of aldehydes with excellent diastereo- and enantioselectivities. Acetaldehyde can be employed as a suitable nucleophilic aldehyde. Successful electrophilic aldehydes are ethyl glyoxylate, chloroacetaldehyde, dichloroacetaldehyde, chloral, α-alkyl-α-oxo aldehyde, trifluoroacetaldehyde, glyoxal, alkenyl aldehyde, alkynyl aldehyde, and formaldehyde. Some of the aldehydes are commercially available as a polymer solution, an aqueous solution, or in the hydrated form. They can be used directly in the asymmetric aldol reaction as a commercially available form, which is a synthetic advantage. Given that the obtained aldol products possess several functional groups along with a formyl moiety, they are synthetically useful chiral building blocks. 相似文献
145.
Daigo Hayashi Dr. Tomohiro Tsuda Prof. Dr. Ryo Shintani 《Angewandte Chemie (International ed. in English)》2023,62(50):e202313171
A palladium-catalyzed skeletal rearrangement of 2-(2-allylarylsilyl)aryl triflates has been developed to give highly fused tetrahydrophenanthrosilole derivatives via unprecedented 1,5-C−Pd/C−Si bond exchange. The reaction pathways can be switched toward 4-membered ring-forming C(sp2)−H alkylation by tuning the reaction conditions to give completely different products, fused dihydrodibenzosilepin derivatives, from the same starting materials. The inspection of the reaction conditions revealed the importance of carboxylates in promoting the C−Pd/C−Si bond exchange. 相似文献
146.
An automated direct assay for the simultaneous determination of unconjugated estetrol, estriol, cortisone and cortisol in serum and amniotic fluid, using high-performance liquid chromatography with electrochemical detection and ultraviolet detection, has been developed. The analysis time is ca. 1 h. This system offers good reproducibility with low coefficients of variation (estetrol, 2.3%; estriol, 2.3%; cortisone, 2.6%; cortisol, 1.9%). Detection limits are low enough for routine determinations (estetrol and estriol, 150 pg; cortisone and cortisol, 5 ng). Comparison of the values measured by the present method and by radioimmunoassay revealed significant correlations for estetrol (r = 0.787, p less than 0.01), estriol (r = 0.957, p less than 0.01), cortisone (r = 0.956, p less than 0.01) and cortisol (r = 0.865, p less than 0.01). This system proved to be valuable in monitoring feto-placental function. 相似文献
147.
148.
149.
Tsukiho Hayashi Ayumi Osawa Takehiro Watanabe Yoshiko Murata Atsushi Nakayama Kosuke Namba 《Tetrahedron letters》2017,58(20):1961-1964
1,3a,6a-Triazapentalene (TAP)-labeled enterobactin was developed as an iron ion sensor. 3-Acetylated-TAP was successfully introduced to the catechol ring of enterobactin, a well-recognized siderophore secreted by various Gram-negative bacteria. The fluorescence of TAP-labeled enterobactin decreased gradually as the amount of Fe3+ ion as an additive was increased, and 1.2 equiv of Fe3+ ion completely quenched the fluorescence. In clear contrast, when other metal ions were used, the fluorescence of TAP-labeled enterobactin remained even at 5.0 equiv. 相似文献
150.