Pyrromethenone 1b, the C,D-ring segment of both phytochrome (Pr) and phytochromobilin (PΦB) has been prepared in a highly efficient fashion beginning with 2-acetyl-butyrolactone (8). The key steps involved conversion of 8 to the Z-enol triflate 9, followed by Pd o catalyzed coupling with trimethylsilylacetylene, p-chlorophenylselenide ring opening, and amidation, to afford ring-D synthon 11 having the proper geometry and oxidation state for conversion to 1b.