10.1016/S0040-4020(01)97399-5
The research focuses on the cycloaddition reactions of sulfonylisothiocyanates with α,β-disubstituted enamines. The purpose of the study was to investigate the formation of cycloadducts and the corresponding dipoles, with a particular emphasis on understanding the structural changes these compounds undergo in different solvents and the factors influencing these transformations. The conclusions drawn from the study indicate that the formation of cycloadducts, rather than dipoles, can be attributed to steric effects, and that the structure of the adducts in solution is significantly influenced by solvent polarity. The researchers also observed a rapid equilibrium between the ring and dipole forms of the compounds, with the rate of conversion being fast compared to the NMR time scale. Key chemicals used in the process include sulfonylisothiocyanates, enamines, tosylisocyanates, and various organic solvents such as CDCl3, CD3CN, and liquid SO2, as well as perchloric acid and acetanhydride for protonation reactions.
10.1002/jhet.5570380125
The research investigates the reactions of various heterocycles with N-bromosuccinimide (NBS) in the presence or absence of water to achieve side chain versus ring bromination, aiming to synthesize important brominated heterocyclic synthons. The study explores different conditions, such as using perchloric acid, which leads to the exclusive formation of a new dibromo aminopicoline (1f) not obtained by other methods. The presence of water droplets in the reaction accelerates the rate of bromination for most heterocyclic compounds, potentially by increasing solvent polarity and maintaining a more uniform distribution of free radicals. The protecting groups on the heterocycles, such as acetyl or 4-nitrobenzoyl, also influence the ratio of side chain versus ring bromination. NBS, benzoyl peroxide, perchloric acid, and acetonitrile are key chemicals in this research, playing crucial roles in the bromination process and the formation of specific products.
10.1007/BF00479904
The research focuses on the synthesis of benzo[c]pyrilium salts with a cyclopolyether substituent and their conversion to isoquinoline derivatives. The key chemicals involved in the research include homoveratric acid and benzo-15-crown-5 as starting compounds. These compounds react in polyphosphoric acid to form ketone I. Carboxylic acid anhydrides, specifically acetic or propionic anhydride, along with perchloric acid, are used to convert ketone I into benzo[c]pyrilium perchlorates (IIa and IIb). Finally, ammonium carbamate is employed to transform these perchlorates into the desired isoquinoline derivatives (IIIa and IIIb). The study explores the potential of these compounds for developing new biologically active substances that can penetrate biological membranes or influence selective ion transfer in living organisms.
10.1007/BF00503592
The study investigates the bisacylation of the anhydride and esters of 4-methyl-1,2,3,4-tetrahydrophthalic acid using carboxylic acid anhydrides in the presence of perchloric acid, resulting in the formation of 1,3-dialkyl-6,7-dicarboxy-5,6,7,8-tetrahydro-2-benzopyrylium salts. The anhydride and esters of 4-methyl-1,2,3,4-tetrahydrophthalic acid serve as the substrates, while carboxylic acid anhydrides act as acylating agents. Perchloric acid is used as a catalyst to facilitate the reaction. The study also explores the reactions of the obtained pyrylium salts, including their recyclization under the action of nucleophiles, and develops a convenient method for synthesizing 6,7-dicarboalkoxy-5,6,7,8-tetrahydroisoquinolines. The research aims to further the understanding of the chemistry of pyrylium salts and their potential applications in synthesizing biologically active compounds.
10.1021/ic0492800
The study focuses on the synthesis, characterization, and structural analysis of copper(II)-thiosulfate complexes with tripodal tetraamine ligands, specifically tren, Bz3tren, Me6tren, and Me3tren. The reaction of [Cu(L)(H2O)]2+ with thiosulfate in aqueous solution results in a color change indicative of thiosulfate coordination to Cu(II). The research explores the formation of complexes, their stability, and the impact of different ligands on the oxidation of thiosulfate. Single-crystal X-ray diffraction analyses were conducted on three thiosulfate complexes, revealing a trigonal bipyramidal geometry around the copper(II) center. The study also includes the determination of thiosulfate binding constants for each Cu(II)-amine complex, with the aim of finding alternatives to the traditional cyanidation process in gold processing. The results show that the complexes with Bz3tren and Me3tren exhibit the highest thiosulfate binding constants reported to date, while the complex with Me6tren is less stable and more prone to oxidize thiosulfate. This research contributes to the development of more environmentally friendly and efficient gold-processing methods.
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O:Oxidizing agent;
