1-Oxo-3,3,7,8-tetramethyl-2,3-dihydrodipyrrin-9-(10H)-carbonsaeure-tert-butylester 、
2,7-Dimethyl-3-ethyl-9-formyl-dipyrrin-1-on-8--propionsaeureamid 以62%的产率得到1,19-Dioxo-17-ethyl-3,3,7,8,13,18-hexamethyl-1,2,3,19,23,24-hexahydro-21H-bilin-8-
-propionsaeureamid