Oxidation of aromatic compounds: XVI. Radical cations derived from acetylenic compounds with electron-withdrawing groups: Reactions and ESR parameters
摘要:
One-electron oxidation of aryl-substituted acetylenes ArC equivalent to CX where X is an electron-withdrawing group gives different products, depending on the X substituent. Acetylenic substrates with medium-strength electron-withdrawing substituents, X = CO2R, COAr, COR, PO(OEt)(2), give rise to tetrasubstituted ethenes X(ArCO)C=C(COAr)X. Compounds with strong electron-withdrawing groups (X = COCF3, COCO2R, CN) are converted into furan derivatives. Probable mechanisms of transformations of ArC equivalent to CX radical cations into the final products are discussed. Radical cations derived from disubstituted acetylenes were characterized by ESR spectroscopy.
Abstract An efficient decarboxylative sulfonylation of arylacetylenic acids with sodium arylsulfinates has been achieved by an electro-oxidative strategy. This novel protocol offers a simple, efficient, and green route to a series of arylacetylenic sulfones in moderate yields under metal-free and external oxidant-free conditions. Graphical Abstract
We describe Cu-catalyzed intermolecular alkynylation and allylation of unactivated C(sp3)–H bonds with singly occupied molecular orbital-philes (SOMO-philes) via hydrogen atom transfer (HAT). Employing N-fluoro-sulfonamide as a HAT reagent, a set of substituted alkene and alkyne compounds were synthesized in high yields with good regioselectivity and functional-group compatibility. Late-stage functionalization
radical‐mediated C−H alkynylation reaction of inactivated alkanes was described. The reaction features mild operation condition and wide substrate scope, and affords the corresponding products in moderate to good yields. Notably, The presence of 4‐cyanopyride N‐oxide was key to the success of the reaction. Cyclohexane are more easily to be functionalized in this reaction than toluene, which could be rationally
An efficient synthesis of diversely functionalized furans is developed via Cu-mediated intermolecular annulative couplings of acetylenic sulfones and activated methylenes, which provides a straightforward and atom-economic way to tetrasubstituted furan derivatives in good yields.
Studies on Hydrozirconation of 1-Alkynyl Sulfoxides or Sulfones and the Application for the Synthesis of Stereodefined Vinyl Sulfoxides or Sulfones
作者:Xian Huang、Dehui Duan、Weixin Zheng
DOI:10.1021/jo0111154
日期:2003.3.1
Z-beta-sulfonyl alpha,beta-unsaturated ketones, and Z-beta-alkynyl vinyl sulfones. Although the reaction mechanisms are still not clear, the neighboringgroupparticipation of the sulfinyl or sulfonyl group may be playing an important role in this unique hydrozirconation reaction.