Counterattack reagents sodium trimethylsilanethiolate and hexamethyldisilathiane in the bis-O-demethylation of aryl methyl ethers

New methods were developed for removal of two methyl groups from aryl methyl ethers. Treatment of an aryl methyl ether containing two methoxy units (i.e., 1, 3, 5, 7, 9, 11 or 13) with ∼2.5 equiv of Me 3 SiSNa in 1,3-dimethyl-2-imidazolidinone at 185°C in a sealed tube gave the corresponding aryl alcohol (i.e., 2, 4, 6, 8, 10, 12, or 14) in 78-96% yields after aqueous workup. Also, Me 3 SiSSiMe 3 was found useful for bis-O-demethylation of aromatic compounds containing one free hydroxyl group and two methoxy units (e.g., 11 and 13). Thus 11 and 13 reacted with 1.5 equiv of NaH and then with 1.5 equiv of Me 3 SiSSiMe 3 at 185°C in a sealed tube to afford triols 13 (75%) and 14 (72%), respectively. In these bis-O-demethylations, Me 3 SiSNa and Me 3 SiSSiMe 3 act as counterattack reagents