DFT Analysis and Synthesis of Medicinally Important Pyrrolo[2,3-d]Pyrimidines by Using Thiamine Hydrochloride as a Recyclable Organocatalyst in Aqueous Media

A facile, environmentally benign and proficient route has been developed for the diverse synthesis of pyrrolo[2,3-d]pyrimidine derivatives followed by heterocyclization starting from Amino uracil, arylgyoxal and malononitrile/thiols. Readily available thiamin hydrochloride organocatalyst was used as a green promoting medium. As well as the reaction progress was taken place under aqueous media. This procedure also offers a base and metal free approach which endowed high yields with better functional group tolerating ability and mild reaction conditions. Further, methodology had a widescope with recyclability and reuse of thiamin hydrochloride. DFT/TD-DFT calculations with B3LYP/6-311G++ level of theory were used to study the optimized geometry and HOMO-LUMO energy of the synthesized compounds (4b and 6i).