A three-way regioselective synthesis of amino acid decorated imidazole, purine and pyrimidine derivatives by multicomponent chemistry starting from prebiotic diaminomaleonitrile

Amino acid decorated imidazole, pyrimidine and purine derivatives, resembling analogues of peptide nucleic acid's building blocks, have been synthesized by a three-way multicomponent chemistry of diaminomaleonitrile, one of the most studied chemical precursors in prebiotic chemistry. The regioselectivity of the multicomponent reaction between diaminomaleonitrile, trimethyl orthoacetate and a selected panel of α-amino acids, was controlled by the energy source used for triggering the condensation. Imidazole derivatives were obtained under thermal condition, while photochemical and combined photothermal conditions afforded pyrimidine and purine derivatives, respectively. The three synthetic pathways were independent of each other, the type of product being controlled by the chemical intermediates prevailing in the reaction mixture. In addition to the synthetic potential of these multicomponent reactions in the preparation of a large variety of heterocycles, the control of the synthesis of peptide nucleic acid's building blocks, simply by changing the nature of the energy source, further enlarged the chemical complexity available in prebiotic conditions for the emergence of pristine pre-genetic codes.