排序方式: 共有27条查询结果,搜索用时 0 毫秒
21.
22.
Boriss Strumfs Kirils Velikijs Romans Uljanovs Stanislavs Sinkarevs Ilze Strumfa 《International journal of molecular sciences》2022,23(11)
Highly functionalized aziridines, including compounds with aromatic moieties, are attractive substrates both in synthetic and medical areas of chemistry. There is a broad and interesting set of synthetic methods for reaching these compounds. Aziridination represents the most explored tool, but there are several other more specific, less well-known, but highly promising approaches. Therefore, the current review focuses on recently described or updated ways to obtain 3-arylated aziridines via different non-aziridination-based synthetic methods, reported mainly since 2000. The presented methods belong to two main directions of synthesis, namely, cyclization of open-chain substrates and rearrangement of other heterocycles. Cyclization of open-chain substrates includes the classic Gabriel-Cromwell type cyclization of halogenated substrates with amines, base-promoted cyclization of activated aminoalcohols (or its analogues), and the oxidative cyclization of β-dicarbonyls. Rearrangements of other heterocycles are presented as the Baldwin rearrangement of 4-isoxazolines, the cycloaddition of 1.3-dipoles or dienes to 2H-azirines, and the addition of C- and N-nucleophiles to the double bond of azirines. 相似文献
23.
Marion P. Krug Laurance L. Oden Peter A. Romans 《Metallurgical and Materials Transactions A》1975,6(4):997-1002
The solid state reactions in the Hf-Ta system were investigated by high-temperature X-ray diffraction, differential thermal
analysis, and electron probe microanalysis. The results support a phase diagram with a monotectoid at about 40 at. pct Ta
and an isotherm at 1083°C. A small miscibility gap was observed between about 40 and 80 at. pct Ta with a maximum temperature
of about 1150°C. 相似文献
24.
In an attempt to select an appropriate fire-resistant hydraulic fluid for use in Naval applications, two approaches were used: (1) development of a shear-resistant, drag-reducing colloid dispersion to determine if it had anti-misting properties, and (2) use of a water-in-oil emulsion loaded to high levels of water. While the dispersion of lithium phenylstearate colloid had demonstrated high drag reducing activity in previous work and would therefore presumably exhibit anti-misting characteristics, it failed to produce the desired fire-suppressive effect. The water-in-oil emulsion, on the other hand, showed promising fire-resistant properties in a flammability testing device. 相似文献
25.
Boriss Strumfs Romans Uljanovs Kirils Velikijs Peteris Trapencieris Ilze Strumfa 《International journal of molecular sciences》2021,22(18)
Aziridination reactions represent a powerful tool in aziridine synthesis. Significant progress has been achieved in this field in the last decades, whereas highly functionalized aziridines including 3-arylated aziridine-2-carbonyl compounds play an important role in both medical and synthetic chemistry. For the reasons listed, in the current review we have focused on the ways to obtain 3-arylated aziridines and on the recent advances (mainly since the year 2000) in the methodology of the synthesis of these compounds via aziridination. 相似文献
26.
Boriss Strumfs Jekaterina Hermane Sergey Belyakov Artjoms Sobolevs Kirils Velikijs Romans Uljanovs Peteris Trapencieris Ilze Strumfa 《International journal of molecular sciences》2021,22(23)
N,N-Dimethylaziridine-2-carboxamides react with organolithium reagents yielding 2-aziridinylketones. The reaction with one equivalent of organolithium compound is selective to amide carbonyl at a low (−78 °C) temperature. These ketones, in reaction with organolithium reagents, give symmetrical and unsymmetrical aziridinyl carbinols. The usage of excess phenyllithium may serve as a special N-Boc-protecting group cleavage method for acid-sensitive substrates. 相似文献
27.