21418-04-2Relevant articles and documents
Chemoenzymatic synthesis of novel C-ribosylated naphthoquinones
Blauenburg, Bastian,Oja, Terhi,Klika, Karel D.,Metsae-Ketelae, Mikko
, p. 2377 - 2382 (2013)
The biological activity of many natural products is dependent on the presence of carbohydrate units, which are usually attached via an O-glycosidic linkage by glycosyltransferases. Recently, an exceptional C-ribosylation event was discovered in the biosynthesis of the polyketide antibiotic alnumycin A. The two-step process involves initial attachment of d-ribose-5-phosphate to the polyaromatic aglycone by the C-glycosynthase AlnA and subsequent dephosphorylation by AlnB, an enzyme of the haloacid dehalogenase family. Here, we tested 23 unnatural substrates to probe the C-ribosylation reaction. The chemoenzymatic synthesis of C-ribosylated juglone, 7-methyl juglone, monomethyl naphthazarin, 8-chloro-7-methyl juglone, and 9-hydroxy-1,4-anthraquinone revealed the importance of a 1,4-quinoid system with an adjacent phenolic ring in order for reaction to occur. To further rationalize the molecular basis for reactivity, factors governing substrate recognition were investigated by NMR binding experiments. Additionally, the suitability of substrates for nucleophilic substitution was assessed by molecular modeling using density functional theory (DFT) calculations.
Total synthesis of the spiroketal naphthoquinone (±)-diepoxin σ
Wipf, Peter,Jung, Jae-Kyu
, p. 1092 - 1093 (2007/10/03)
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Regiospecific Synthesis of Quinizarin and Naphthazarin Derivatives by Cycloaddition
Cameron, Donald W.,Feutrill, Geoffrey I.,McKay, Peter G.
, p. 2095 - 2109 (2007/10/02)
The diene (E)-1,1,4-trimethoxybuta-1,3-diene underwent regiospecific cycloaddition to derivatives of 2(3)-chloro-1,4-naphthoquinone.The resulting adducts were aromatized to give 1,4-dioxygenated anthraquinones.The latter were obtained as derivatives of quinizarin dimethyl ether or of quinizarin monomethyl ether depending on the conditions of aromatization.Cycloaddition of the diene to non-halogenated naphthoquinones proceeded similarly, orientation being controlled by substituents in the benzenoid ring.Analogous reaction of the diene with benzoquinones gave 5,8-dioxygenated naphthoquinones (naphthazarins), generally in limited yield.The procedure has been applied to synthesis of the mould metabolites helminthosporin and cynodontin