(Z)-1,3,4,5-Tetrahydro-3,3,3',4'-tetramethyl-5-oxo-2,2'-pyrromethen-5'-carbonsaeure-tert-butylester   、                                                                                      3-Ethyl-4-methyl-5-methoxy-2-(3,4-dimethyl-5-formyl-2-pyrrolyl-methylen)-1H-pyrrol                                                                                                                                                              在
                                                                                                                                                                                 
三氟乙酸                                                                                                                                  作用下,
                                                                                                                                                                                                                            以95%的产率得到(4Z,9Z,15Z)-17-Ethyl-1-oxo-19-methoxy-3,3,7,8,12,13,18-heptamethyl-1,2,3,23-tetrahydro-1H-bilin