Diethyl 4-ethyl-1,5-dihydro-3-methyl-5-oxo-2H-pyrrol-2-ylphosphonate and 2-ethylidene-3-methyl-1-thiosuccinimide as D-and A-rings of phycocyanobilin dimethyl ester could be synthesized by using commercially available mucochloric acid as a starting material in good yields.