The synthesis of natural products and biologically active molecules is one of the main applications of organic chemistry. Many natural products with valuable biological properties have low abundance in natural sources. Therefore, they need to be synthesized in sufficient quantities that their properties and activities can be studied. Chapter 1 describes synthesis of a library of biologically active compounds which are currently used in RNA imaging studies. Chapter 2 describes the synthesis of the procyanidin A skeleton. Procyanidins are important natural products with various biological activities. Chapter 3 describes a method for the preparation of anthocyanidins, natural products which possess valuable biological properties.