O-Naphthoquinone

The synthetic procedure described is based on that reported earlier for the synthesis on a smaller scale of anthracene, benz[a]anthracene, chrysene, dibenz[a,c]anthracene, and phenanthrene in excellent yields from the corresponding quinones. Although reduction of quinones with HI and phosphorus was described in the older literature, relatively drastic conditions were employed and mixtures of polyhydrogenated derivatives were the principal products. The relatively milder experimental procedure employed herein appears generally applicable to the reduction of both ortho- and para-quinones directly to the fully aromatic polycyclic arenes. The method is apparently inapplicable to quinones having an olefinic bond, such as o-naphthoquinone, since an analogous reaction of the latter provides a product of undetermined structure (unpublished result). As shown previously, phenols and hydro-quinones, implicated as intermediates in the reduction of quinones by HI, can also be smoothly deoxygenated to fully aromatic polycyclic arenes under conditions similar to those described herein. 

Heating o-nitrosophenols with hydroxylamine is reported to give furazans, naphtho[l,2-c]furazan (95) being formed from both l-nitroso-2-naphthol and 2-nitroso-l-naphthol, presumably by oximation of the tautomeric o-naphthoquinone monooximes and subsequent dehydration. Compound (95) has also been prepared by oxidation, using alkaline ferri-cyanide or hypochlorite, of l-amino-2-nitroso- and 2-amino-l-nitroso-naphthalene. This latter approach is suitable for heterocyclic fused furazans thus 4,6-diamino-5-nitrosopyrimidine is converted into the furazanopyrimidine (96) by oxidation with lead tetraacetate (71JOC3211). In a similar reaction alkaline hypochlorite oxidizes o-nitrosoacetaniiide to benzofurazan in quantitative yield. 

Naphthol is generally oxidized to give o-naphthoquinones through radical intermediates A and B, respectively. 

Although the proposed mechanism seems attractive and all the fragmentation products, except for the o-naphthoquinone 293, have been identified, it still remains to be demonstrated that the merocyanine forms of spiropyrans and spirooxazines have the ability to induce formation of singlet oxygen, a species on which the entire mechanistic scheme has been based. (This question is being addressed by Guglielmetti s group). 

In 2000, Otani et al. isolated two furano-o-naphthoquinones, (-)-nocardione A and (—)-nocardione B (142 and 143, Figure 5.27 and 5.28) as new tyrosine phosphatase inhibitors with moderate antifungal and cytotoxic activities. Due to the scarcity of the materials (only 8 mg of 142 and 0.3 mg of 143 were obtained from 4.5 L of the culture broth of Nocardia sp. TP-AO 248), their absolute configuration remained unknown. In order to solve this problem, we undertook a synthesis of optically active 142 and 143 with known absolute configuration.35... 

In addition, ring strain 139> and intramolecular interactions 25,29,139) may be important. Spectra of biacetyl and benzil showed marked changes when determined 175> in silica gel-cyclohexane slurry. The shift of the n,n maximum to shorter wavelength in the series o-benzoquinone, o-naphthoquinone, 9,10-phenanthrenequinone has been discussed by Murrell 103>. 

Determination of structural features. The ultraviolet spectrum has been of value in the determination of the structure of several vitamins. Thus the presence of an o-naphthoquinone system in vitamin K was first detected by this means. Also the 4-methylthiazole and the 2 5-dimethyl-... 

One of the early examples of an intramolecular Diels-Alder reaction of benzynes involved cycloaddition to a furan that was tethered to the benzyne moiety . Diazoti-zation of anthranilic acid 669 gave in 86% yield the cycloadduct 670, which was subsequently converted to the o-naphthoquinone 671 (mansonone E 7 steps) as well as to the structurally related mansonones F and I and biflorin. ... 

Lately, Soliman et al. [67] replaced isocyanates in the above reactions by the monoanils of benzil (90), o-naphthoquinone or triketones (such as 91) only to obtain the corresponding azetidinones (92, 93) with each of ylides 2, 82 or 88 (Scheme 19). However, reactions were not run at 2 1 (imine ylide) stoichiometry. 

Positive polyimide resists have also been developed. One example starts from a solnble polymer [60] with a formulation analogons to a novolac positive resist o-naphthoquinone diazide was used as a photoreactant linked to the polymer (Figure 6.25). 

Keywords Bioorthogonal reaction Photo-triggered reaction Photoclick Tetrazole Nitrile imine Azirine Cyclopropenone o-Naphthoquinone methide o-Quinodimethanes Hetero Diels-Alder reaction... 

In 2011, Popik and co-workers reported photochemical dehydration of 3-hydroxy-2-naphthalenemethanol (o-naphthoquinone precursor, NQMP, 79) derivatives to o-naphthoquinone methides (oNQMs, 80) [78, 79]. The in situ generated reactive intermediate oNQM underwent facile cycloaddition with vinyl ethers (81) to form photostable benzochromans (82) (Scheme 12). NQMP (79) has two major absorption bands at 275 nm (log s = 4.06) and 324 nm (log s — 3.70) thus it can be photoactivated with either low pressure mercury lamp (254 nm) or fluorescent tubes (300 and 350 nm). The quantum yield of the photoactivation was very high (< 300 = 0.17 0.02 for 79). The in situ generated oNQMs was quenched mostly by... 

O-" naphthoquinone imine 1 benzalaniline, phenyl-glyoxylic acid imine, sali-cylaldoxime, benzo-phenone hydrazone, benz-hydrazidine... 

The reaction of l,2-bis(diphenylphosphino)ethane with substimted o-benzoquinones affords bis(6-hydroxycyclohexa-2,4-dienone) derivatives. Treatment of the same reagent with o-naphthoquinone, phenanthrenequinone and acenaphthenequinone gave the respective bis(diphenylphosphoryl)ethylidenes or diacenaphthylenone derivatives. On the other hand, p-quinones react with l,2-bis(diphenylphosphino)methane to yield the corresponding 4-hydroxycyclohexa-2,5-dien-l-ones. ... 

The reaction between o-naphthoquinone methides and thiols has been employed for reversible photochemically-directed surface derivatisation and patterning, through the production of thioether links between the... 

The first synthesis of morphine was reported by Marshall Gates (University of Rochester). It was a remarkable achievement. The plan is outlined briefly here. The idea was that if compound 6 could be obtained, it would be possible to move forward to morphine. In parallel studies it was shown that morphine could be degraded to 6, thus providing a relay point for any synthesis effort, since morphine was in abundant supply and synthetic 6 would no doubt be difficult to obtain in large quantities. Structure 6 could clearly be obtained through a cycloaddition of an appropriate dienophile with 1,3-butadiene. The question is which dienophile. The choice ulitimately became o-naphthoquinone 8. A cycloaddition between this electron-deficient dienophile and 1,3-butadiene would provide 7, which one might convert to 6 via a reductive amination and additional oxidation state adjustments. 

Decarbonylation of o-benzoquinones 374 can be considered as a method of synthesis of CPDNs 375. Photodecarbonylation of o-quinones under UV radiation has a long history, and many mechanistic studies have been performed and described in the literature (Scheme 6.91a) [222]. Another ring contraction to an indenone 376 from o-naphthoquinone 377 in aqueous H2O2 (30%) in the presence of catalytic amount of iodine in acetonitrile has also been reported (Scheme 6.91b) [223]. 

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