Di‐, tri‐, and tetrathienyl‐substituted polycyclic aromatic fluorophores were prepared from different aryldi‐, aryltri‐, or aryltetrahalides by a simple and fast Suzuki coupling. The reaction was optimized for the synthesis of the desired materials on multigram scale. The coupled products were converted into the corresponding iodides through iodination with N‐iodosuccinimide. The iodides turned out to be versatile starting materials for applications, such as periodic mesoporous organosilica syntheses. They were converted into a variety of new trimethoxysilyl arenes by using a very efficient Pd‐mediated C–Si cross‐coupling, which was also extended to the corresponding thienyl bromides by using a dimeric PdI catalyst. All compounds were characterized by 1H NMR, 13C NMR, 29Si NMR, and ATR‐IR spectroscopy and HRMS.
A phosphonic acid functionalized triphenylphosphine rhodium complex was synthesized and grafted onto neat superparamagnetic iron oxide nanoparticles. The material was investigated by elemental analysis, IR spectroscopy, thermogravimetric analysis, XRD, N2‐physisorption analyses, and TEM measurements. The obtained hybrid material could be used as a catalyst for the hydrogenation of alkenes with excellent yields and a broad substrate scope. The catalyst can be reused ten times without any loss of activity. According to the results from X‐ray absorption spectroscopy, it is likely that formation of Rh nanoparticles occurs during the reaction.
4-Pentenols (dihomoallylic alcohols) are oxidized by cobalt(II)-activated dioxygen in solutions of dimethyl disulfide and cyclohexa-1,4-diene to afford methylsulfanyl (CH3S)-functionalized tetrahydrofurans in up to 74% yield. The reaction is a cascade, composed of oxidative alkenol cyclization providing tetrahydrofuryl-2-methyl radicals, which are trapped in dimethyl disulfide. Homolytic methylsulfanyl substitution by carbon radicals is a slow reaction, as exemplified by the rate constant of k(SCH(3)) = 3 × 10(4) M(-1) s(-1) (70 °C) derived from competition kinetics for the reaction between dimethyl disulfide and the trans-2-phenyltetrahydrofuryl-5-methyl radical. Methylsulfanyl-cyclizations therefore are experimentally performed in neat dimethyl disulfide, containing the minimum amount of cyclohexa-1,4-diene necessary for attaining almost quantitative alkenol conversion. The oxidative tetrahydrofuran synthesis occurs with noteworthy (>99%) 2,5-trans-stereoselectivity, as shown by the synthesis of diastereomerically pure 2,3- and 2,3,3-substituted 5-(methylsulfanyl)methyltetrahydrofurans from stereodefined 1,2-di- and 1,2,2-trisubstituted 4-pentenols. Changing the chemical nature of the disulfide reagent or the alkenol extends the scope of alkylsulfanyl-cyclization to ethylsulfanyl-cyclization, allylsulfanyl-transfer, or tetrahydropyran synthesis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.