A proposed chemical model for the prebiogenesis of tetrapyrrole macrocycles relies on the condensation of a 3-alkyl-substituted 2, 4-diketone and an α-aminoketone to form a pyrrole equipped for subsequent self-condensation leading to porphyrinogens. The condensation of acyclic reactants can proceed via competing Knorr (desired) and Fischer–Fink (undesired) pathways. Here, the Knorr and Fischer–Fink pathways are quantitated using (1) ...
[Seeman, Jeffey I.; Paine III, John B.; Secor, Henry V.; Im, Hoong-Sun; Bernstein Journal of the American Chemical Society, 1992 , vol. 114, # 13 p. 5269 - 5280]
