Naphthoquinones and Polycyclic Quinones

Some new reagents have been introduced for the preparation of 1,4- and 

2- naphthoquinones. These have been summarised in Table 5.3 (refs.51-57). 

3- Naphthoquinones have been generated by a non-oxidative route involving bromination with N-bromosuccinimide in the 1-position of the respective 2-keto tautomer as the mono t-butyidimethylsilyl derivative, treatment of the bromo compound with tetra-n-butylammonium fluoride and trapping of the product as a norbornadiene adduct, in a yield of 64% in the case of the 1,4-diphenyl member (ref.58). 

7-Phenanthrenequinones have been produced from the coupling of cis-4,4 -dihydroxystilbenes, (in one example obtained through a Wittig reaction with 

5-trimethoxybenzaldehyde and 2,3,4-trimethoxybenzylphosphoniumbromide), followed by selective demethylation and oxidation with the silver(l) cation, (AgjO) (ref.59). 

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