2- Hydroxynaphthoquinones

A major problem in the use of the antiparasitic 4-hydroxyquinolones and 2-hydroxynaphthoquinones is resistance that can develop with extraordinarily high frequency. It may be attributable to their mitochondrial site of action, which is known to have a high frequency of mutation. 

Pd(II)/Cu(I)-promoted reactions of the 2-hydroxynaphthoquinone ylide 283 with terminal alkynes or their tributylstannane derivatives afford moderate yields of furonaphthoquinones 284 (Scheme 81) (97TL837). It was... 

The reaction of resorcinols with a,P-unsaturated aldehydes and ketones catalysed by ethylenediamine diacetate has been used to synthesise the naturally occurring chromenes confluentin and daurichromenic acid <05OBC3955, 05TL7539>. 2-Hydroxynaphthoquinone behaves similarly providing a useful route to pyranonaphthoquinones <05S3026>. 

Hydroxynaphthoquinones. Under Friedel-Crafts reaction conditions aroy-lacetic esters react with oxalyl chloride to give the quinone skeleton. The ester group is removable through saponification. 

Hydroxynaphthoquinone 2-Hydroxy-1,4-naphthoquinone. See Lawsone p-((4-Hydroxy-1-naphthyl) azo) benzenesulfonic acid, monosodium salt. See Acid orange 20 4-(2-Hydroxy-1 -naphthylazo) benzenesulfonic acid sodium salt. See D C Orange No. 4 Acid orange 7... 

CAS 83-72-7 EINECS/ELINCS 201-496-3 Synonyms Cl 75480 Flower of paradise Henna 2-Hydroxy-1,4-naphthalenedione 2-Hydroxynaphthoquinone 2-Hydroxy-1,4-naphthoquinone 1,4-Naphthalenedione, 2-hydroxy- 1,4-Naphthoquinone, 2-hydroxy- Natural orange 6 Classification Substituted naphthoquinone Definition Chemical present in henna Empirical CioHeOs... 

Intramolecular [2 + 2] photocycloaddition of the quinone moiety of quinopimaric acid (48) to the isopropyl-substituted double bond leads to a polycyclic cage compound." 2-Hydroxynaphthoquinones undergo a formal [3 + 2] photocycloaddition with different cyclic alkenes, delivering chiral products (49). In the presence of a chiral template, a limited enan-tioselectivity is observed." ... 

CYP158A2 Streptomyces coelicolor A3(2) E.g 1SE6, 1T93, IS IF, 2D0E Flaviolin, 4-phenylimidazole, 2-hydroxynaphthoquinone Oxidative phenolic coupling in flaviolin polymerization E.g., [195,197,198]... 

The one-pot three-component reaction of 2-hydroxynaphthoquinone, aromatic aldehydes and ethyl 4,4,4-trifluoro-3-oxobutanoate in the presence of ammonium acetate and acetic acid affords a series of 2-trifluoromethylated benzol ]chroman derivatives (13S2193).Various allyl silanes are suitable for an annulation reaction with 1-naphthoquinone-2-methide, formed through an FeCl3-mediated transformation of l,4-epoxy-l,4-dihydronaphthalenes, to prepare benzo[/z]chromans, in moderate to good yields (Scheme 36) (13AGE1515). 

A similar reaction was published by Song et al. in 2013 (Scheme 13.29) [47]. 2-Hydroxynaphthoquinone 75 was reacted with aromatic aldehydes 97 and ethyl 4,4,4-lrifluoro-3-oxobutanoate 98 catalyzed by a mixture of ammonium acetate and acetic acid (25mol% each). A Knoevenagel-Michael addition sequence was followed by hemiketal formation to give the desired product 99 in moderate to good yields. Dehydration of the product yielded the 4 f-pyran derivatives. 

Senboku, H., Kajizuka, Y., Kobayashi, K., Tokuda, M., and Suginome, H., Photoinduced molecular transformations. 160. Furan annelation of 2-hydroxynaphthoquinone involving photochemical addition and radical fragmentation xeclusion of the intermediacy of [2-1-2] cycloadduct in a one-pot formation of furanoquinones by the regioselective 3-1-2 photoaddition of hydroxyquinones with alkenes. Heterocycles, 44, 341,1997. 

The Formation of Fused Furan Rings via Tandem P-Fragmentation-Cyclization of Cyclobutanoxyl Radicals Generated from [2- -2]-Photoadducts Derived from 4-Flydroxycoumarin, 3-(or 4-)-Hydroxy-quinolinone or 2-Hydroxynaphthoquinone withA alkenes... 

The photolysis of the hypoiodites generated from the cyclobutanols, derived from the [2-l-2]-photo-addition of 2-hydroxynaphthoquinone with alkenes (A) and of 2-aminonaphthoquinone with vinyl arenes (B) in the presence of mercury(II) oxide and iodine induced regioselective P-fragmentations of the cyclobutanoxyl radicals to give a 2,3-dihydronaphtho[2,3-h]furan-4,9-dione and its [ l,2-h]furan-4,5-dione isomer (Scheme 76). 

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