Organic Photochemistry in the Construction of Heterocyclic Compounds

Photochemical transformations have long been known as methods of constructing organic molecules through electronic excitations with examples spanning all areas of organic synthesis [1, 2]. However, its application to organic heterocyclic synthesis has yet to be highlighted as a powerful alternative to thermal reactions. Heterocyclic ring systems have been extensively investigated for their biological activities and new ways of constructing more unusual and complex ring systems is fast becoming a significant challenge for contemporary organic chemists in order to explore novel molecular space. This review includes up-to-date highlights of where organic photochemistry has been applied to the synthesis of heterocyclic compounds and what chemistry learnings have arisen from their discovery. Current techniques of photochemistry in flow are also explored as a scalable alternative to traditional batch-wise processes and other merits of photo-flow chemistry described.