A concise synthesis of pyrrolo[2,3-d]pyrimidine through I/DMSO promoted cascade annulation.

An attractive approach for the preparation of pyrrolo[2,3-d]pyrimidines has been developed via I/DMSO promoted cascade annulation of 6-amino-1,3-dimethyluracil with aurones. The reaction involves Michael addition, iodination, intramolecular nucleophilic substitution, and spiro ring opening in one-step process, and affords a series of natural product analogues containing pyrrolo[2,3-d]pyrimidine in good yields (up to 99%). Additionally, this protocol exhibits the advantages of high atom economy, inexpensive catalyst, readily available materials, convenient operation and applicability for large-scale synthesis.