Abstract A short, succinct route to biologically active and medicinally important pyrrolo[2,3-d]pyrimidines has been developed starting from readily available acyclic aldehydes. A very efficienttwo step sequence involving a Knoevenagel condensation followed by copper mediated 1,4-conjugate of vinyl magnesium bromide sets up the acyclic precursor. Then, guanidine cyclization followed by a palliduim catalyzed amination reaction or ozonolytic cleavage of the vinyl substituent followed by guanidine cyclization and intramolecular imine formation complete the synthesis.