91563-65-4Relevant academic research and scientific papers
Dihydroartemisinin ether derivatives and use thereof
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Paragraph 0175-0177, (2017/07/01)
The invention relates to the technical field of medicine, and specifically relates to nitrogen-substituted dihydroartemisinin phenyl ether, optical isomers thereof and a preparation method thereof; pharmaceutical compositions with the derivatives as activ
2-Diazo-1-(4-hydroxyphenyl)ethanone: A versatile photochemical and synthetic reagent
Senadheera, Sanjeewa N.,Evans, Anthony S.,Toscano, John P.,Givens, Richard S.
, p. 324 - 341 (2014/02/14)
α-Diazo arylketones are well-known substrates for Wolff rearrangement to phenylacetic acids through a ketene intermediate by either thermal or photochemical activation. Likewise, α-substituted p-hydroxyphenacyl (pHP) esters are substrates for photo-Favorskii rearrangements to phenylacetic acids by a different pathway that purportedly involves a cyclopropanone intermediate. In this paper, we show that the photolysis of a series of α-diazo-p- hydroxyacetophenones and p-hydroxyphenacyl (pHP) α-esters both generate the identical rearranged phenylacetates as major products. Since α-diazo-p-hydroxyacetophenone (1a, pHP N2) contains all the necessary functionalities for either Wolff or Favorskii rearrangement, we were prompted to probe this intriguing mechanistic dichotomy under conditions favorable to the photo-Favorskii rearrangement, i.e., photolysis in hydroxylic media. An investigation of the mechanism for conversion of 1a to p-hydroxyphenyl acetic acid (4a) using time-resolved infrared (TRIR) spectroscopy clearly demonstrates the formation of a ketene intermediate that is subsequently trapped by solvent or nucleophiles. The photoreaction of 1a is quenched by oxygen and sensitized by triplet sensitizers and the quantum yields for 1a-c range from 0.19 to a robust 0.25. The lifetime of the triplet, determined by Stern-Volmer quenching, is 31 ns with a rate for appearance of 4a of k = 7.1 × 10 6 s-1 in aq. acetonitrile (1:1 v:v). These studies establish that the primary rearrangement pathway for 1a involves ketene formation in accordance with the photo-Wolff rearrangement. Furthermore we have also demonstrated the synthetic utility of 1a as an esterification and etherification reagent with a variety of substituted α-diazo-p- hydroxyacetophenones, using them as synthons for efficiently coupling it to acids and phenols to produce pHP protect substrates. The Royal Society of Chemistry and Owner Societies.
Palladium-catalyzed intermolecular α-arylation of zinc amide enolates under mild conditions
Hama, Takuo,Culkin, Darcy A.,Hartwig, John F.
, p. 4976 - 4985 (2007/10/03)
The intermolecular α-arylation and vinylation of amides by palladium-catalyzed coupling of aryl bromides and vinyl bromides with zinc enolates of amides is reported. Reactions of three different types of zinc enolates have been developed. The reactions of
