Hydroxyl Protection. III. Synthesis and Cleavage of 2-(Phenylseleno)Ethyl Ethers

Abstract

During a quest of new hydroxyl-protecting groups, our attention was focused at one time on the 2-(phenylseleno)ethyl residue. It has been established that selenides are responsive to oxidation by H₂ O ₂,² O ₃,³IO₄,⁴etc., to afford selenoxides; aryl alkyl selenoxides undergo facile thermal decomposition⁵ at room temperature or below. Thus starting from 2-(phenylseleno)ethyl ethers (1), the reaction sequence would lead to vinyl ethers and PhSeOH via the intermediates (2). As vinyl ethers are easily hydrolyzed on contact with mineral acids to acetaldehyde and alcohols, the value of the PhSeCH₂CH₂ group for blocking hydroxyl becomes clear.