Synthesis and singlet oxygen reactivity of 1,2-diaryloxyethenes and selected sulfur and nitrogen analogs

1,2-Diaryloxyethene has recently been proposed as a linker in singlet oxygen-mediated drug release. Even though 1,2-diaryloxyethenes look very simple, their synthesis was not an easy task. Previous methods are limited to symmetric molecules, lengthy step and low yield. We report on a facile synthetic method not only for 1,2-diaryloxyethenes but also their sulfur and nitrogen analogs in yields ranging from 40 to 90% with more than 90% purity at the vinylation reaction. Most recently, light-controlled drug release systems were proposed, where singlet oxygen generated from low energy light and a photosensitizer cleaves electron-rich alkenes, e.g. 1,2-diaryloxyethene. However, the synthesis of 1,2-diaryloxyethene was not well established. Herein, we report a facile synthesis of 1,2-diaryloxyethenes and its sulfur and nitrogen analogs. Model compounds were prepared in four steps from 4-phenylphenol via Ullman-type coupling reaction.