Photocarboxylation of Arylated 2 H ‐Azirines Exploiting Continuous Flow Technology

Abstract A robust and efficient continuous flow set‐up is presented for the orchestrated use of CO 2 gas and photochemistry in flow mode. This study explores the catalyst‐free cycloaddition between azomethine ylides generated in situ from simple 2 H ‐azirines and CO 2 . Using UV−A light (365 nm) as energy source and CO 2 as inexpensive and abundant building block provides an attractive strategy affording isomeric oxazolones which were subsequently aromatised to yield novel oxazole products in a convergent manner. Continuous flow processing substantially improves the reaction performance allowing for the safe exploitation of this intriguing transformation. This enables the effective fixation of CO 2 to generate valuable building blocks that can be scaled to gram scale with ease.