Aerial Oxygen-Driven Selenocyclization of <i>O</i>-Vinylanilides Mediated by Coupled Fe³⁺/Fe²⁺ and I₂/I⁻ Redox Cycles

Abstract

In the past decade, selenocyclization has been extensively exploited for the preparation of a wide range of selenylated heterocycles with versatile activities. Previously, selenium electrophile-based and FeCl3-promoted methods were employed for the synthesis of selenylated benzoxazines. However, these methods are limited by starting material availability and low atomic economy, respectively. Inspired by the recent catalytic selenocyclization approaches based on distinctive pathways, we rationally constructed an efficient and greener double-redox catalytic system for the access to diverse selenylated benzoxazines. The coupling of I2/I− and Fe3+/Fe2+ catalytic redox cycles enables aerial O2 to act as the driving force to promote the selenocyclization. Control and test redox experiments confirmed the roles of each component in the catalytic system, and a PhSeI-based pathway is proposed for the selenocyclization process.

Keywords

• diselenide
• <i>o</i>-vinylanilide
• redox cycle
• aerial oxygen
• multivalent metal
• benzoxazine