Oxidation quinone synthesis

Quinone synthesis. Two laboratories12 have found that the adducts formed by addition of an aryl-, alkynyl-, or heteroaryllithium to a cyclobutenedione rearrange when heated (138-160°) to hydroquinones, which are usually isolated as the quinone after air or chemical oxidation. The rearrangement involves an interme-... 

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). 

Quinone synthesis. The oxovandium complex is a catalyst for aerial oxidation of polynuclear arenes and aryl ethers. 

---