L. Liguori et al., Electrophilic aromatic alkylation by hydroperoxides. Competition between ionic and radical mechanisms with phenols, J ORG CHEM, 64(24), 1999, pp. 8812-8815
Tertiary hydroperoxides have been utilized for the electrophilic alkylation
of activated aromatic substrates, particularly phenols and phenol ethers.
Cumyl (1) and tert-butyl (2) hydroperoxides have shown a greatly different
behavior as concerns the catalysis and the regioselectivity. The best catal
yst for 1 is TiCl4, which is completely inactive with 2. With the latter an
effective catalyst is FeCl3, which, however, can give rise to a combinatio
n of electrophilic and radical reactions with alkyl phenols. 2,2'-Dihydroxy
-3,3'-di-tert-butyl-5,5'-dimethyldiphenyl is obtained in high yields from p
-cresol.