PREPARATIONS AND REACTIONS OF CRESOL DIANIONS AND DIMETHYLPHENOL TRIANIONS (ANISOLE, ALKYL PHENOL, CYCLOPHANE).

Abstract

With n-BuLi/t-BuOK (Lochmann's base), protons are removed from the hydroxyl and methyl groups of cresols to give cresol dianions in yields of 85% (o), 95% (m), and 40% (p). These dianions react with alkyl halides, MeSiCl, Bu₃Sn Cl, CO₂, and oxidizing agents at carbon only, and with dialkyl sulfates at both carbon and oxygen. Thus phenol derivatives bearing primary alkyl groups can be prepared from the corresponding methylphenol via cresol dianions. Dimethylphenol trianions were prepared with Lochmann's base from all six isomers of dimethylphenol. 3,5-Dimethylphenol trianion was prepared in the best yield (80%); 2,3-, 2,4-, 2,5-, 2,6-, and 3,4-dimethylphenol trianions were prepared in 19.5%, 19%, 52%, 36%, and 44% yields, respectively. The common side products were dianions and tetraanions (in the latter, the fourth proton was usually pulled from the ring ortho to oxygen). These trianions were reacted with dimethyl sulfate to give anisole derivatives. 3,5-Dimethoxytoluene monoanion was reacted with n-BuBr to give a mixture of O,O'-dimethylolivetol (40%) and 4-butyl-3,5-dimethoxytoluene (34%).