High efficiency microwave flow chemistry toward synthesis of functional materials and pharmaceutical cores

Microwave (MW) heating benefits organic synthesis by affording higher product yields in shorter time periods than conventional heating (CH), yet it suffers from poor scalability and is limited to polar solvents in typical batch mode reactors.^1,2 An auto-frequency tunable microwave (AFT MW) continuous flow (CF) reactor has been developed and commercialized by SAIDA FDS Inc. and Pacific Microwave Technologies (PMT).³ ATF MW compensates for changes in the microwave absorption properties (permittivity, ) with increasing temperature^1,2,4 affording excellent temperature and process control. Moreover, it is applicable to heating of non-polar solvents. Organic synthesis using an ATF MW CF reactor is a rapidly developing research field in Japan and beyond.^5,6,7 Herein, we report recent applications of a microwave flow reactor using a solid-state semiconductor MW generator toward high efficiency synthesis of functional materials and pharmaceutical cores. Attention is drawn to examples where AFT MW heating has been compared to CH in flow, and where its application has expediated reaction optimization.