Synthesis of the tit1e compounds by 1,4-addition of an organocopper reagent is described.The reaction of n-butyllithium-N,N,N',N'-tetramethylethylene diamine complex 1 and the iodovinyl compound 3 in ethyl ether at -70℃ affords in high yield the vinyllithium compound 4.The organocopper reagent 5,prepared from 4,reacted with 6 to afford after chromatography the dl-11-deoxy-PGE₁ methyl ester 7a and its 15-epimer 7b in 80 -85% yield.Similarly,the organocopper reagent 13 prepared from 11,reacted with 6 to give dl-15(R,S)-11-deoxy-15-methyl-PGE₁ methyl ester in 39% yield.