This book describes the development of two kinds of continuous-flow transformation using heterogeneous catalysts, and explains how they can be applied in the multistep synthesis of active pharmaceutical ingredients. It demonstrates and proves that fine chemicals can be synthesized under continuous-flow conditions using heterogeneous catalysis alone. Importantly, the book also proposes a general concept and strategy for achieving multistep flow synthesis and developing heterogeneous catalysts, and shows that commercially available anion exchange resin can be used as a water-tolerant strong base catalyst for various types of continuous-flow aldol-type reaction. Reviewing the state of the art in heterogeneous catalysis in flow chemistry – a “hot topic” and rapidly developing area of organic synthesis – the book will provide readers with a deeper understanding of fine chemical flow synthesis and its future prospects.