Unexpected Mild Protection of Alcohols as 2-O-THF and 2-O-THP Ethers Catalysed by Cp2TiCl Reveal an Intriguing Role of the Solvent in the Single- Electron Transfer Reaction

Abstract

A method for the conversion of primary, secondary and tertiary alcohols into the corresponding THF ethers at room temperature and primary and secondary alcohols into the corresponding THP ethers, has been developed using titanium(III) species generated from a catalytic amount of titanocene dichloride or (4R,5R)-(–)-2,2-dimethyl-α,α,α ,α -tetra(1-naphth-yl)-1,3-dioxolane-4,5-dimethanolatotitanium(IV) dichloride: acetonitrile adduct together with manganese(0) as a reductant and bromoform in THF or THP as the solvent. A radical mechanism is proposed for this transformation revealing an intriguing role of the solvent in the single-electron transfer reactions catalysed by the low valent TiIII system.