in situ generated by conjugate addition of organocopperreagents to the chiral oxygenated cyclopentenone synthon, R-4, gives the three-component coupling products in a regiospecific manner. The intermediary nitronate anion 17 is further transformed into the nitro compound or 6-oxo-PGE1 (19) in a single pot. This coupling reaction is applicable to syntheses of naturally occurring prostaglandins such