Nucleic acids as templates and catalysts in chemical reactions: target-guided dynamic combinatorial chemistry and in situ click chemistry and DNA/RNA induced enantioselective reactions.

Nucleic acids play crucial roles in transferring cellular information and gene regulations. DNA and RNA molecules have been associated with multiple human diseases and thus offer opportunities for exploring small molecule-based therapeutics. However, developing target-selective molecules possessing well-defined biological activity, has always been challenging. In the current scenario, where the world is continuously experiencing outbreaks of new infectious diseases, it is always important to expand the scope of chemical toolsets to override conventional drug discovery strategies for developing therapeutically relevant drug candidates. The template-directed synthetic approach has emerged as a promising tool for rapid drug discovery. It allows a biological target to template the selection or synthesis of its ligands from a pool of reactive fragments. There are two main template-directed synthetic strategies: thermodynamically controlled dynamic combinatorial chemistry (DCC) and kinetically controlled target-guided in situ click chemistry. Though discovered only two decades ago, these techniques have proven their usefulness for nucleic acid targets, as exemplified by the increasing number of applications with therapeutically important DNA and RNA targets. However, nucleic acid templated synthetic techniques are relatively unexplored in drug discovery compared to protein targets. In this review article, we have presented a detailed discussion of all the reported nucleic acid templated synthetic studies to portray the great potential of this strategy for efficient hit discovery and lead optimisation. This article would assist in expanding the scope and utility of this strategy through a summary of the advancements and emerging applications. Additionally, a brief overview of the catalytic potential of nucleic acids in asymmetric synthesis has been provided to give a valuable vision of the use of nucleic acids to induce enantioselectivity in chiral drug-like candidates.