21418-04-2

Upstream product

• 475-38-7 5,8-Dihydroxy-1,4-naphthoquinone 
• 74-88-4 methyl iodide 
• 106-51-4 p-benzoquinone 
• 58070-21-6 (E)-1,1,4-trimethoxy-buta-1,3-diene 
• 128038-44-8 4,8-dimethoxy-1,5-diformylnaphthalene 
• 10075-63-5 1,5-dimethoxynaphthalene 
• 129447-52-5 4,8-Dimethoxy-1,5-naphthalindiol 
• 15013-16-8 5,8-dimethoxynaphthoquinone 

Downstream Products

• 161690-58-0 8-Hydroxy-5-methoxy-3-phenyl-3a,9a-dihydro-naphtho[2,3-d]isoxazole-4,9-dione 
• 81194-58-3 Benzoic acid 5,8-dihydroxy-4-methoxy-naphthalen-1-yl ester 
• 7414-92-8 Tetrangulol 
• 81194-55-0 5-(benzoyloxy)-8-methoxy-1,4-naphthoquinone 

Relevant academic research and scientific papers

Chemoenzymatic synthesis of novel C-ribosylated naphthoquinones

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.

Formal total synthesis of (+)-diepoxin σ

The highly oxygenated antifungal anticancer natural product (±)-diepoxin σ was prepared in 10 steps and in 15% overall yield from O-methylnaphthazarin. Highlights of the synthetic work include an Ullmann coupling and a possibly biomimetic oxidative spirocyclization for the introduction of the naphthalene ketal as well as the use of a retro-Diels-Alder reaction to unmask the reactive enone moiety in the naphthoquinone bisepoxide ring system. A novel highly bulky chiral binaphthol ligand was developed for a boron-mediated Diels-Alder reaction that constitutes a formal asymmetric total synthesis of (+)-diepoxin σ.

Synthesis of 4,8-Dimethoxy-1,5-naphthalenediol and Its Oxidation to 4,8-Dimethoxy-1,5-naphthoquinone

Formation of the new 1,5-naphthoquinone 3 was achieved by methylation of 1,4,5,8-naphthalenetetrol (1a) and oxidation of the dimethylether 1c obtained thereof.In the presence of water, 3 yields the monoether 5a.Methylation of binaphthazarin (6a) seems to proceed in a similar manner.

Regiospecific Synthesis of Quinizarin and Naphthazarin Derivatives by Cycloaddition

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