Arylthiols as Highly Chemoselective and Environmentally Benign Radical Reducing Agents
摘要:
Arylthiols serve as excellent environmentally benign reducing agents for organotellurium, organostibine, and organobismuthine compounds under radical conditions. Both small molecules and macromolecules possessing these heteroatorn groups are reduced under moderate thermal conditions to give near quantitative yields in most cases. The reduction shows high chemoselectivity with respect to the heteroatorn compounds the reactivity decreases in the order alkylbismuthines, alkylstibines, and alkyltellurides, while simple alkyl iodides could not be reduced. Alkyltellurides are selectively reduced in the presence of alkyl iodides even when an excess amount of arylthiol is used. Furthermore, alkylstibines are also selectively reduced in the presence of alkyltellurides. Moreover, the reduction conditions are compatible with the presence of a variety of polar functional groups in the substrates, products, and solvents, which are not tolerant under ionic and metal-catalyzed conditions. Carbon-carbon bond formation is possible with use of the carbon-centered radicals that are generated. The results clearly reveal the synthetic utility of arylthiols in organic synthesis.
A powerful electrophilic activator for organotellurium compounds was developed. Phenyltellanyl triflate (PhTeOTf) prepared in situ from dibromophenyl(phenyltellanyl)telluride and AgOTf selectively activated various organotellurium compounds in the presence of aromatic compounds yielding the corresponding Friedel–Crafts reaction products. Polymer-end organotellurium compounds were also activated by PhTeOTf providing the corresponding end-functionalized polymers.
An alternative approach for the synthesis of aryl–alkyl tellurides: reaction of aryl iodides with metal alkyltellurolates promoted by CuI
作者:Márcio S. Silva、João V. Comasseto
DOI:10.1016/j.tet.2011.09.014
日期:2011.11
Aryliodides react with metal organotellurolates in tetrahydrofuran/dimethylformamide in the presence of CuI (5 mol %) or CuI (5 mol %) and 1,10-phenanthroline (10 mol %) to afford the corresponding aryl–alkyl tellurides in good yields.
Experimental and theoretical studies on formal σ-bond metathesis of silyl tellurides with alkyl halides
作者:Shigeru Yamago、Kazunori Iida、Jun-ichi Yoshida
DOI:10.1016/j.jorganchem.2006.05.066
日期:2007.1
Silyl tellurides reacted with alkylhalides under mild thermal conditions to give the corresponding alkyl tellurides and silylhalides in good to excellent yields. Substitution took place much faster in polar solvents, such as acetonitrile, than that in non-polarsolvents. After removal of the volatile silyl halides and solvent under vacuum, the essentially pure divalent organotellurium compounds were