10.1021/acscombsci.8b00118
The research focuses on the synthesis and evaluation of a small library of triazolyl polyphenols, correlating their antioxidant activity and stability with the number and position of hydroxyl groups on the aromatic rings. The study involves the synthesis of 1,2,3-triazoles disubstituted with polyphenol groups at 1,4-positions using a metal-free method, with subsequent demethylation to yield polyphenolic compounds. The antioxidant activity of these compounds was assessed using in vitro assays, namely the oxygen radical absorbance capacity (ORAC) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS) tests, while their in vivo effects were evaluated using a Saccharomyces cerevisiae model organism assay. The stability of the compounds in aqueous solutions was also monitored over a two-month period. Reactants included various anilines, acetophenones, and tosylhydrazide, while analyses utilized fluorescence spectrometry for ORAC, spectrophotometry for ABTS, and colony forming units for the yeast assay.
10.1021/ja00204a015
The research focuses on the total synthesis of d,l-methynolide, the aglycon of the macrolide antibiotic methymycin, utilizing sulfur-mediated ring expansion technology. The purpose of this study was to develop a synthetic approach that relies on sequential 2,3-sigmatropic rearrangements of stabilized sulfonium ylides to build cyclic sulfides of varying ring sizes and to achieve remote stereocontrol through the predictable conformational properties of medium-sized ring intermediates and the stereoelectronic effect of sulfur α to ketone carbonyl. The successful route involved the ring expansion of sulfonium ylide to an eight-membered sulfide, followed by conversion to alcohol and reduction of the double bond to form the saturated analogue. Key chemicals used in the process included sulfonium ylides, sulfides, alcohols, and various reagents for protection, oxidation, and reduction steps, such as lithium ethyl boranolate (LiEt3BH), methyltriphenylphosphonium bromide, potassium tert-butoxide, and p-toluenesulfonylhydrazide, among others. The conclusions of the research detailed the successful synthesis of d,l-methynolide and a similar route to ClO-epi-methynolide, demonstrating the efficacy of the sulfur-based strategy for remote stereocontrol in complex macrocycle synthesis.
10.1021/acs.joc.9b02088
The study investigates the synthesis of novel soft-Lewis basic complexants that are crucial for the separation of minor actinides from lanthanides in nuclear fuel cycle processes. The researchers employed a metal and oxidant-free [3 + 2] dipolar cycloaddition reaction to create 21 new examples of these complexants. The key chemicals involved include terminal ethynyl pyridines acting as dipolarophiles and tosylhydrazides serving as dipoles. The reaction was optimized using DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) as a base in toluene solvent at 80 °C, achieving modest regioselectivity and yields ranging from 42% to 68%. The study also explored the scope of the reaction with various substituents on both the dipolarophile and dipole, demonstrating the method's versatility. Additionally, the researchers performed a tenfold scale-up of the reaction and conducted functional group interconversions to enhance the complexants' properties. The synthesized complexants were characterized using various techniques, including NMR, IR, and HRMS, and their structures were confirmed through single-crystal X-ray crystallography. Density functional theory (DFT) calculations were used to understand the regioselectivity and electronic properties of the reactants and products. The study aims to improve the efficiency of nuclear fuel cycle processes by developing new complexants with enhanced performance in liquid-liquid separation and subsequent transmutative processes.
10.1016/0040-4039(91)80677-X
The research aims to develop a new method for converting dicarbonyl compounds into alkenes, specifically focusing on the synthesis of phenanthrenes from 2-(2-formylphenyl)benzaldehydes. The study explores various routes to achieve this transformation, including heating the dilithium or disodium salts of the bistosylhydrazones derived from the aldehydes. The researchers initially attempted methods such as the Bacon procedure and titanium coupling but faced challenges, especially with steric hindrance in the synthesis of 4,5-dimethoxyphenanthrene. They then explored the formation of bis-diazoalkanes from bistosylhydrazones, which upon heating, could cyclize to form phenanthrenes. Tosylhydrazine is used as a key reagent to convert the 2-(2-formylphenyl)benzaldehydes into their corresponding bistosylhydrazones. Sodium hydride (NaH) is employed to deprotonate the bistosylhydrazones, forming their sodium salts. The study concludes that this new method is effective for the preparation of sterically hindered phenanthrenes and represents a significant advancement in the field of alkene formation from dicarbonyl compounds.
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