Fig. 1: Ipecac alkaloid biosynthesis in C. ipecacuanha and A. salviifolium based on the literature.

Either secologanin 1 or secologanic acid 2 is coupled with dopamine 3 in a Pictet–Spengler reaction to yield deacetylisoipecoside DAII (S-epimer) 4a and deacetylipecoside DAI (R-epimer) 4b or the respective acids deacetylisoipecosidic acid DAIIA (S-epimer) 5a and deacetylipecosidic acid DAIA 5b. Derivatized forms of the R-epimer are the N-acetylated ipecoside found in C. ipecacuanha and 6-O-Me-deacetylipecosidic acid or 7-O-Me-deacetylipecosidic acid found in A. salviifolium. The S-epimer undergoes a series of reactions including methylations, deglycosylation, reduction and, in the case of deacetylisoipecoside, deesterification to form protoemetine 8, which is then derivatized to form downstream alkaloids in both plants as shown. Compounds specific to C. ipecacuanha are shown in blue; compounds specific to A. salviifolium are shown in magenta.