Substituted anthraquinones, modifier

Substituted anthraquinones. In the latter figure, 9>5% 2-propanol in carbon dioxide as the mobile phase results in a separation very similar to that with 5.51 2-methoxyethanol in carbon dioxide. In both cases 1,8-dlhydroxyanthraquinone elutes with and right after anthraquinone so those components are not separated, even at much lower modifier concentrations the retention times of anthraquinone and 1,8-dihydroxyanthraquinone increase together with the tailing of the 1,8-dihydroxyanthra-qulnone becoming more and more pronounced as the modifier concentration is decreased. However, with chloroform as the modifier, those two components are significantly split apart, with... 

Chen and coworkers published a formal [3 + 3]-type reaction to give highly substituted cyclohexenes 8. This domino process consists of an allylic-allylic alkylation of an a,a-dicyanoalkene derived from 1-indanone and Morita-Baylis-Hillman carbonates, following an intramolecular Michael addition, by employing dual orga-nocatalysis of commercially available modified cinchona alkaloid (DHQD)2AQN If (hydroquinidine (anthraquinone-l,4-diyl) diether) and (S)-BINOL. The cyclic adducts... 

Most aromatic compounds in plants are derived from shikimic acid metabolism many of these substances are phenols. Compounds derived from this pathway are extensively modified and considered under other classes of plant secondary metabolites. Although many types of secondary compounds are produced from intermediates of the shikimic acid pathway (e.g., certain naphthoquinones and anthraquinones discussed in Chapter 6), most are derived from four aromatic amino acids phenylalanine, tyrosine, anthranilic acid, and tryptophan. Aromatic compounds that arise from the shikimic acid pathway usually can be distinguished from those of other origins by their substitution patterns and by a knowledge of the compounds with which they co-occur. 

Salimi A, Eshghi H, Sharghi H, Golabi SM, Shamsipur M. Electrocataljrtic reduction of dioxygen at the surface of glassy carbon electrodes modified by some anthraquinone substituted podands. Electroanalysis 1999 11 114—9. 

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