This book highlights recently discovered aspects of “middle-size molecules,” focusing on (1) their unique bio-functions on the basis of derivatives and conjugates of natural products, saccharides, peptides, and nucleotides; (2) the synthesis of structurally complex natural products; (3) special synthetic methods for π-conjugated functional molecules; and (4) novel synthetic methods using flow chemistry. Given its scope, the book is of interest to industrial researchers and graduate students in the fields of organic chemistry, medicinal chemistry, and materials science.