20816-46-0Relevant articles and documents
Substituted phenacyl molecules and photoresponsive polymers
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, (2016/06/28)
Substituted phenacyl molecules are provided and employed to create molecules and polymers/copolymers that exhibit photoresponsiveness. In some instances, the substituted phenacyl molecule is incorporated into the polymer/copolymer backbone, and photoirradiation of the polymer/copolymer causes the substituted phenacyl group to break down and the polymer/copolymer to undergo degradation. In other instances, the substituted phenacyl molecules extend as a side chain from the polymer/copolymer backbone. In yet other instances the substituted phenacyl molecules extend as a side chain from the polymer/copolymer backbone, and a drug or polymer additive is linked to the photoresponsive substituted phenacyl group such that photoirradiation releases the drug or additive. In yet other embodiments the substituted phenacyl molecules extend as a side chain from the polymer/copolymer backbone, and serve to link the polymer/copolymer to another polymer/copolymer backbone, and photoirradiation breaks the links.
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.
Synthesis of [4-14C]-pelargonidin chloride and [4- 14C]-delphinidin chloride
Kraus, Michael,Biskup, Ellen,Richling, Elke,Schreier, Peter
, p. 1151 - 1162 (2007/10/03)
The synthesis of [4-14C]-pelargonidin chloride and [4- 14C]-delphinidin chloride via [formyl-14C]-2-(benzoyloxy)- 4,6-dihydroxybenzaldehyde, ω,4-diacetoxyacetophenone and ω,3,4,5-tetraacetoxyacetophenone is described. The first step comprised labelling of the carbonyl group of 2-(benzoyloxy)-4,6-dihydroxybenzaldehyde, verifying that the coupling with ω,4-diacetoxyacetophenone or ω,3,4,5-tetraacetoxyacetophenone under hydrogen chloride atmosphere resulted in the formation of [4-14C] labelled anthocyanidins. Copyright