Synthesis of Sulfone Containing‐Spirocycles, ‐Pentafulvene Dyes and Their Photophysical Properties

Synthesis of sulfur‐containing spiro[4.4]nonane compounds has been achieved by the reaction of 2‐phenacyl‐1,3‐indandiones with 3‐(phenylsulfonyl)propiolate in highly regioselective manner by using CsF as a base. The synthesized sulfur‐containing spiro[4.4]nonanes were further converted to extended pentafulvene p‐systems in an acidic medium. Photophysical properties of the synthesized sulfone‐based pentafulvene dyes are also delineated in this article.