2-Pivaloylamino-pyrrolo[2,3-d]pyrimidine-4-one (I) is chlorinated to (II) in refluxing POCl3. Subsequent, Stille coupling of (II) with tributyl vinyltin gives the vinyl pyrrolopyrimidine (III), which is further reduced to the corresponding ethyl derivative (IV) by catalytic hydrogenation over Pd/C. Regioselective iodination of (IV) by means of N-iodosuccinimide provides (V). Aryl iodide (V) is then subjected to palladium-catalyzed cross-coupling with trimethylsilylacetylene (VI), leading to the silylethynyl adduct (VII). Desilylation of (VII) employing tetrabutylammonium fluoride furnishes intermediate (VIII).
Coupling of acetylene (VIII) with diethyl N-(4-iodobenzoyl)-L-glutamate (IX) gives rise to the disubstituted acetylene (X). This is then hydrogenated to (XI) in the presence of Pd/C. Finally, hydrolysis of (XI) under alkaline conditions leads to the title compound.