This chapter discusses the synthesis and biosynthesis of Cinchona alkaloids—the chemistry behind it. Generally, the Cinchona alkaloids are found in the bark and leaves of Cinchona and Remijia species. Quinidine has been isolated, although in small quantities, from the bark of two plants of the Anonaceae family Enantia polycarpa Engl. et Diels and E. pilosa Exell. Cinchonidine and other Cinchona alkaloids have been extracted from the leaves of Olea europaea. A new alkaloid, dihydroquinamine, has recently been isolated from the leaves of Isertia hypoleuca Benth. This is the first plant that contains a 2,2′-indolylquinuclidine alkaloid as the major alkaloid. The crystalline alkaloid C19H26O2N2 shows color reactions characteristic of indole alkaloids. Shortages of the Cinchona alkaloids from natural sources led to new efforts at total synthesis. The chapter discusses reinvestigation of the Rabe–Woodward synthesis of quinine. The formation of the quinuclidine moiety in the Rabe–Woodward synthesis was also reinvestigated. © 1973, Academic Press, Inc.