摘要:
1-(alpha-Alkoxybenzyl)benzotriazoles undergo reversible ionization in solution to a benzotriazolyl anion (Bt-) and carboxonium cations PhCH:O+R. These cations can attack the beta-carbon atom of enol ethers to give cation adducts which add the Bt- to form new alpha-(benzotriazol-1-yl)alkyl ethers in which the carbon chains are extended by an alpha-ethoxybenzyl group. Reactions of these adducts with Grignard reagents produce the corresponding 1,3-diethers in high yield. Reduction of the adducts with lithium aluminum hydride gives the corresponding diethers via substitution of the benzotriazolyl moiety with a hydrogen atom or 1-(3-alkoxyalkyl)benzotriazoles via substitution of the alpha-alkoxy group, depending on the reaction conditions and the nature of the adduct.