10.1023/A:1015334703526
The research focuses on the chemistry of urea nitro derivatives, specifically the synthesis of nitramide from N,N'-dinitrourea and subsequent reactions of nitramide. The study developed convenient procedures for synthesizing nitramide based on urea through the hydrolysis of N,N'-dinitrourea, which is highly reactive and sensitive to mechanical disturbance. The experiments involved various reactants such as urea, N,N'-dinitrourea, water, sulfuric acid, ammonium nitrate, and water-saturated solvents with low dielectric constants. The analyses used to monitor the reactions and characterize the products included infrared (IR) and ultraviolet (UV) spectroscopy, as well as kinetic measurements to determine the rate constants of the hydrolysis reactions. The study also explored nitramide's decomposition in acid media and its reactions with formaldehyde, ethyl acetate, and acetic anhydride, leading to the formation of various compounds like dinitramide, methylenedinitramine, and N-nitroacetamide.
10.1016/S0040-4020(02)00360-5
The research aims to investigate the mechanism of a stereospecific ring contraction of flavanones to form 2-aryl-2,3-dihydrobenzo[b]furan-3-carboxylates using iodobenzene diacetate (PIDA) in the presence of sulfuric acid in trimethyl orthoformate (TMOF). The study's conclusions are based on evidence from NMR, CD, and chiral HPLC, which support a mechanism involving the formation of a hypervalent iodine intermediate followed by an aryl migration. The research demonstrates that the transformation is highly stereoselective and controlled by the configuration of the C-2 center, leading to the major product trans-methyl 2-aryl-2,3-dihydrobenzo[b]furan-3-carboxylate (4a). Key chemicals used in the process include PIDA, sulfuric acid, TMOF, and various flavanones.
10.1021/jo00191a003
The study explores a direct method for the periodination of aromatic compounds using periodic acid (HIO?) and iodine in concentrated sulfuric acid. This method allows for the exhaustive iodination of unactivated aromatic substrates such as benzene, nitrobenzene, benzoic acid, chlorobenzene, phthalic anhydride, and toluene, converting them into their respective periodo derivatives. The study also reports the conversion of benzonitrile to pentaiodobenzamide. The direct periodination method is compared favorably to the existing mercuration/iododemercuration sequence in terms of reaction time and purity of products. The study highlights the versatility of the method, demonstrating that partially iodinated products can be obtained under less vigorous conditions. Additionally, the study discusses the limitations of the method, noting that certain activated aromatics and easily oxidized substrates do not fare well under these conditions. The research provides detailed experimental procedures and characterizations of the synthesized compounds, contributing to the field of organic chemistry by offering a more efficient route for the preparation of polyiodinated and periodinated aromatic compounds.
10.3762/bjoc.14.207
The study focuses on the semi-synthesis and insecticidal activity of spinetoram J and its D-forosamine replacement analogues. Spinetoram, derived from fermentation, is a broad-spectrum insecticide that is environmentally friendly and non-toxic to animals and humans. The researchers improved the semi-synthesis process of spinetoram J by using 3-O-ethyl-2,4-di-O-methylrhamnose as both a reaction substrate and a protecting group, which simplified the synthesis steps and reduced costs. They also synthesized a range of D-forosamine replacement analogues and evaluated their insecticidal activities against Plutella xylostella larvae. Although the analogues did not match the potency of spinetoram, some showed only 20–40 times lower activity, with one analogue being nearly as active as spinosad. The findings suggest the potential for developing new insecticides by modifying sugar components in natural products and highlight the importance of the electrical properties of substituents in insecticidal activity.
10.1016/S0040-4039(01)93382-9
The study explores the creation of potential host systems through the annulation of aromatic rings on the cis,syn,cis-triquinane backbone. The researchers used chemicals such as diphenylisobenzofuran for cycloaddition reactions and sulfuric acid for aromatisation processes to transform the triquinane bis-enone into compounds with bis-naphthoannulation. The resulting compounds, designated as 4 and 5, were characterised by their crystal structures, with compound 5 showing a molecular cleft featuring a lipophilic posterior and carbonyl recognition sites. The study highlights the design and synthesis of these novel host systems, which could have applications in molecular recognition and binding studies.
10.1021/ja01492a035
The study investigates the Hofmann-Loffler reaction, which involves the formation of cyclic amines from N-haloammonium ions through a free radical chain mechanism. The researchers examined various aspects of the reaction mechanism, including stereochemistry, hydrogen isotope effects, initiation, inhibition, catalysis, intermediates, and selectivity of hydrogen transfer. Key chemicals involved in the study include N-haloammonium ions, sulfuric acid, and various amines such as N-bromocinine, N-bromo-N-methyl-2-butyiamine, and N-chloro-N-alkylamides. The study provides evidence for a free radical chain mechanism involving intramolecular hydrogen transfer as a propagation step, and it explores the influence of factors such as acid concentration, molecular oxygen, and different substituents on the reaction's efficiency and selectivity. The findings contribute to a deeper understanding of the Hofmann-Loffler reaction and its potential applications in the synthesis of cyclic amines.
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C
C:Corrosive;
