The understanding of functional groups is key for the understanding of all organic chemistry. In the tradition of Patai s Chemistry of Functional Groupseach volume in this series treats all aspects of functional groups. Each volume contains a wide range of chapters, touching on theoretical, analytical, synthetic, biological and biochemical, and industrial aspects. Selenium and Tellurium have seen a huge growth in interest. This fourth volume covers again all areas of organic and physical organic chemistry, but it is especially strong on the area of the synthesis of biologically active compounds. This makes this volume especially interesting for medicinal chemists.