A new and versatile synthesis of 5-substituted pyrrolo[2,3-d]pyrimidines

We have developed a new methodology for the construction of 5-substituted pyrrolo[2,3-d]pyrimidines that involves the reduction of a nitroalkane to an oxime using the reducing ability of the Sn(SR3)− species, followed by mild, acid-catalysed deoximation of the resulting adduct using Dowex-H+ resin to form an intermediate aldehyde that spontaneously cyclises to the fused pyrrole ring.