Dibenzofuran ether diaryl

In diaryl ethers (and dibenzofurans), the bond to the less substituted aromatic ring is cleaved.47... 

Oxidation of 2-iodo-4,6-di(terr-butyl)phenol (702) with K3Fe(CN)e in aq. KOH (room temp., 20 min) also provided in 82% yield the corresponding benzoxete 703 probably through o-diphenoquinone. In contrast, similar oxidation of three 2-halo-4,6-di(ferf-butyl)phenols (704, 705 and 706) mainly afforded a dibenzofuran derivative 707 (81%), a mixture of 708 and 709 (23 and 53%, respectively) and a diaryl ether 710 (63%), respectively (Scheme 138). Clearly, iodine and bromine substituents promote the diaryl formation, while chlorine and fluorine substituents prefer to produce diaryl ethers. These results seem to be in good agreement with the ab initio calculations . 

A sequential three-step process consisting of diaryl ether Hthiation, bor-ylation, and hydrolysis transforms dibenzofurans into dibenzoxaborininols 11 (Scheme 5) (2013MI3625)... 

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