A novel synthetic approach to pyrrolo[2,3-d]pyrimidine antifolates

A novel and efficient synthetic method for the synthesis of pyrrolo[2,3-d]pyrimidine antifolates is described. The key reaction of this method is the photo-initiated free radical addition of bromomalononitrile or ethyl bromocyanoacetate to an enol ether to afford the backbone skeleton of the targeted antifolate molecule. The key intermediates 3 or 4 are smoothly converted to the pyrrolo[2,3-d]pyrimidine antifolates 1 or 2 in three steps and in high overall yield.