Pyrrolo[2,3-d]pyrimidine synthesis through activation of N-benzyl groups by distal amides

A new activation mode of CH₂-benzylamino groups has been observed during the preparation of pyrrolopyrimidines from Ugi-Smiles adducts of hydroxypyrimidines. The cyclization proceeds via a formal deprotonation of the N-benzyl group followed by trapping of the resulting anion by the alkyne moiety. The key role of the vicinal amide function during the process was pointed out.