Natural Product-Inspired Therapeutics: Synthesis of Novel Alkylamino-Functionalized Purine Derivatives with Anticancer Applications

Abstract

The development of small-molecule therapeutics that selectively target oncogenic pathways while minimizing systemic toxicity remains a major frontier in medicinal chemistry. The purine ring is widely recognized as a "privileged scaffold" due to its structural homology with endogenous nucleic acids and natural alkaloids. This study details the natural product-inspired design and synthesis of a novel series of amino- substituted purine derivatives derived from a 2,6-dichloropurine template. The synthetic workflow investigated the impact of aliphatic spacer length on the compounds' physical and potential pharmacological properties through two distinct pathways: one involving the reaction of 2,6-dichloropurine with a long-chain flexible nucleophile. Both pathways achieved regioselective nucleophilic aromatic substitution exclusively at the highly electrophilic C-6 position. Comprehensive analytical characterization was conducted to confirm structural integrity and sample homogeneity. Analytical HPLC confirmed high chemical purity for the synthesized monomers and demonstrated a clear relationship between chain elongation and column retention time, indicating optimized lipophilicity in the longer chain variant. LCMS and high-resolution mass spectrometry confirmed the exact molecular weights expected for mono-substituted functionalization, ruling out unwanted dimerization. FTIR spectroscopy verified the successful introduction of the amine linkers via the appearance of diagnostic secondary amine stretching bands, while 1H-NMR definitively proved that the core purine architecture remained intact, showing a sharp, characteristic singlet for the purine ring proton alongside perfectly integrated upfield aliphatic methylene signals. These findings establish a highly efficient, green synthetic route toward structural analogues of active kinase inhibitors, providing a clear chemical framework for subsequent in vitro anti-proliferative evaluations against human cancer cell lines.