Reactions of 2,2-bis(trifluoromethyl)oxirane with alcohols under phase transfer catalysis

It was demonstrated that the reaction of 2,2-bis(trifluoromethyl)oxirane (1) with variety of alcohols could be successfully carried out under phase transfer catalysis conditions using sodium or potassium hydroxide as a base. For example, reaction of CH₃OH, C₂H₅OCH₂CH₂OH, HOCH₂CH₂OH with one or two moles of 1 in the presence of the catalyst [(C₄H₉)₄N⁺HSO₄⁻] gives the corresponding tertiary alcohols R[OCH₂C(CF₃)₂OH]_n (n=1 or 2) in 43-53% yield, along with some O[CH₂C(CF₃)₂OH]₂. Benzyl alcohol and phenol under similar conditions are less active, producing in the reaction with 1 the corresponding adducts ArOCH₂C(CF₃)₂OH in 31-35% yield. Fluorinated alcohols, such as CF₃CH₂OH, ClCF₂CH₂OH, HCF₂CF₂CH₂OH have much higher reactivity towards 1 giving ring opening products in 82-97% yield. Even in the reaction of hindered hexafluoro-iso-propanol the corresponding adduct was isolated in 43% yield. Surprisingly, the reaction of iso-propanol and epoxide 1, results in the formation of O[CH₂C(CF₃)₂OH]₂ as a major product, isolated in 56% yield. Possible mechanism for the formation of the last product was proposed.