3-[5-(3-ethyl-4-methyl-5-oxo-1,5-dihydro-pyrrol-2-ylidenemethyl)-2-formyl-4-methyl-pyrrol-3-yl]-propionic acid   、                                                                                      rac-(Z)-9-tert-Butyl-3-carboxymethyl-2,3-dihydro-2,2,7,8-tetramethyl-dipyrrin-1-one-carboxylate                                                                                                                                                              在
                                                                                                                                                                                 
三氟乙酸                                                                                                                                  作用下,
                                                                                                                                                                                                                            以58%的产率得到(Z,Z,Z)-3-Carboxymethyl-17-ethyl-1,2,3,19,23,24-hexahydro-2,2,7,8,13,18-hexamethyl-1,19-dioxo-21H-bilin-12-propanoic acid