Iodothyronine Deiodinase Mimics. Deiodination of o,o‘-Diiodophenols by Selenium and Tellurium Reagents
摘要:
To better understand, and in the extension mimic, the action of the three selenium-containing iodothyronine deiodinases, o,o'-diiodophenols were reacted under acidic conditions with sodium hydrogen telluride, benzenetellurol, sodium hydrogen selenide, or benzeneselenol and under basic conditions with the corresponding deprotonated reagents. Sodium hydrogen telluride was found to selectively remove one iodine from a variety of 4-substituted o,o'-diiodophenols, including a protected form of thyroxine (T-4) Thus, it mimics the D1 variety of the iodothyronine deiodinases. Sodium telluride was a more reactive deiodinating agent toward o,o'-diiodophenols, often causing removal of both halogens. Benzenetellurol and sodium benzenetellurolate sometimes showed useful selectivity for monodeiodination. However, the products were often contaminated by small amounts of organotellurium compounds. Sodium hydrogen selenide, sodium selenide, benzeneselenol, and sodium benzeneselenolate were essentially unreactive toward o,o'-diiodophenols. To gain more insight into thyroxine inner-ring deiodination, substituted 2,6-diiodophenyl methyl ethers were treated with some of the chalcogen reagents. Reactivity and selectivity for monodeiodination varied considerably depending on the substituents attached to the aromatic nucleus. In general, it was possible to find reagents that could bring about the selective mono- or dideiodination of these substrates.
Efficient and Practical Oxidative Bromination and Iodination of Arenes and Heteroarenes with DMSO and Hydrogen Halide: A Mild Protocol for Late-Stage Functionalization
efficient and practical system for inexpensive bromination and iodination of arenes as well as heteroarenes by using readily available dimethyl sulfoxide (DMSO) and HX (X = Br, I) reagents is reported. This mild oxidative system demonstrates a versatile protocol for the synthesis of aryl halides. HX (X = Br, I) are employed as halogenating reagents when combined with DMSO which participates in the present
Metal-Free, Oxidant-Free, and Controllable Graphene Oxide Catalyzed Direct Iodination of Arenes and Ketones
作者:Jingyu Zhang、Shiguang Li、Guo-Jun Deng、Hang Gong
DOI:10.1002/cctc.201701182
日期:2018.1.23
oxide (GO)‐catalyzed iodination of arenes and ketones with iodine in a neutralmedium was explored. This iodination protocol was performed by using a simple technique to avoid the use of external metal catalysts and oxidants and harsh acidic/basic reaction conditions. In addition, by this method the degree of iodination could be controlled, and the reaction was scalable and compatible with air. This strategy
An in situ acidic carbon dioxide/glycol system for aerobic oxidative iodination of electron-rich aromatics catalyzed by Fe(NO<sub>3</sub>)<sub>3</sub>·9H<sub>2</sub>O
作者:Ran Ma、Cheng-Bin Huang、An-Hua Liu、Xue-Dong Li、Liang-Nian He
DOI:10.1039/c4cy00721b
日期:——
An environmentally benign CO2/glycol reversible acidic system was developed for the iron(III)-catalyzed aerobic oxidative iodination of electron-rich aromatics without the need for any conventional acid additive or organic solvent. Notably, moderate to high isolated yields (up to 97%) of the aryl iodides were attained with comparable regioselectivity when ferric nitrate nonahydrate was used as the catalyst with molecular iodine under 1 MPa of CO2.
Transition metal-free protodecarboxylation of electron rich aromatic acids under mild conditions
作者:Jingxian Fang、Dangui Wang、Guo-Jun Deng、Hang Gong
DOI:10.1016/j.tetlet.2017.10.036
日期:2017.11
A mild and practical method for the transition metal-free protodecarboxylation of aromatic acids using readily available and safe sodium persulfate as initiator was described. This environment-friendly decarboxylation approach was performed at 60 °C in ethanol and could easily scale up to the gram level with a good yield. In Particular, the tandem reactions of decarboxylation and halogenation were