Quinone synthesis nitric acid

There are numerous other examples of the synthesis of quinones employing reagents such as nitric acid, manganese dioxide, salcomine/02, silver oxide, " chromium oxidants, >2 -47... 

Thallium trifluoroacetate has not enjoyed widespread use as a reagent for quinone synthesis, possibly because it is still a relatively new reagent but more probably because of its toxicity. One example of its use lies in the synthesis of metacyclophanes and related compounds as reported by Tashiro et al Thus the r-butylphenol (59) gave the bisquinone (61), while the phenol (60) afforded the monoquinone (62). An alternative and more practical synthesis of the bisquinone (61) for large scale work involved dealkylation to afford the bisphenol (63) which was then treated with sodium nitrite to give the bisoxime (64). Hydrolysis of the bisoxime did not give the quinone (61), but it could be obtained by zinc/acetic acid reduction of the bisoxime followed by oxidation with nitric acid (Scheme 13). 

Several streptonigrin quinoline-quinone analogs have also been synthesized by Rao (16) (Scheme 6) using a modified Friedlander synthesis for construction of the quinoline system. The compound prepared which structurally is most like the natural product is the pyridylquinoline-quinone (59). Chalcone (55), prepared from 3,5-dimethoxybenzaldehyde and 2-acetylpyridine, was nitrated to give (56). Reductive cyclization of (56) with sodium dithionite led to quinoline (57) which upon treatment with nitric acid/sulfuric acid yielded nitroquinone (58) in 50% yield along with 40% of a product of straightforward mononitration. Reduction of the nitro group of (58) and 0-methylation with diazomethane afforded (59). 

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