Pyrroloindoles as Therapeutically Invaluable Agents: A Review on their Diverse Synthetic Methodologies

In the realm of medicinal chemistry, heterocyclic compounds play a vital role due to their diverse pharmacological properties, especially, pyrroloindoles standing out as crucial motifs in drug development. Pyrroloindoles, which are formed by combining indole and pyrrole rings, exhibit unique characteristics and serve as integral components in numerous drugs and natural compounds. The synthesis of pyrroloindoles is challenging due to their complex ring structures and diverse substitution patterns. This comprehensive review compiles various synthetic strategies for obtaining pyrroloindole derivatives via metal-catalyzed reactions; cyclopropanation/ ring opening/ iminium cyclization (CRI reaction); organocatalytic cascade addition-cyclization; 1,3-dipolar cycloaddition; Bronsted acid-catalyzed [3+2] cyclodimerization; ring closure mechanisms; thermally-induced ring-opening and cyclization reactions; condensation reactions; and visible-light photocatalytic asymmetric reactions providing a valuable resource for synthetic organic chemists and researchers interested in the synthesis of pyrroloindoles and their derivatives. These compounds play a pivotal role in drug discovery thus, making this review an indispensable reference. This review explores diverse synthetic methodologies for various pyrroloindoles and pyrroloindolines encompassing over 50 research articles. It delves into structural modifications, functionalization and bioactivity by covering general approaches, transition metal-catalyzed methods, cascade reactions, etc. Recent advances are highlighted, along with challenges and future perspectives. This comprehensive analysis aims to contribute to the understanding and development of pyrroloindole-based therapeutics.image