Synthetic Strategies Toward Naturally Occurring α-Pyrones: A Review of Total Syntheses and Methodological Advances.

Abstract

α-Pyrones constitute an important class of natural products widely distributed in plants, fungi, bacteria, and marine organisms, exhibiting diverse biological activities, including antimicrobial, anticancer, anti-inflammatory, antiparasitic, and phytotoxic effects. Their structural diversity and pharmacological potential have stimulated extensive efforts toward the development of efficient synthetic methodologies. This review provides an overview of the total syntheses of naturally occurring α-pyrones reported between 1984 and 2026, covering structurally diverse subclasses, including styrylpyrones, meroterpenoids, macrocyclic α-pyrones, fused polycyclic systems, and other complex α-pyrone-containing natural products. Particular emphasis is placed on the principal synthetic strategies employed for α-pyrone construction and target assembly, including aldol condensations, crossmetathesis reactions, transition-metal-catalyzed couplings, biomimetic cascade processes, radical cyclizations, Claisen rearrangements, and asymmetric methodologies. The review compares these approaches in terms of synthetic efficiency, stereochemical control, and methodological innovation. Key advances in stereoselective and total synthesis are highlighted, demonstrating how modern synthetic methods have enabled access to increasingly complex α-pyrone architectures with high levels of chemo-, regio-, and stereoselectivity. The review also discusses the contribution of total synthesis to structural confirmation, biological evaluation, and the preparation of analogues for structureactivity relationship studies. Current challenges, including lengthy synthetic sequences, low overall yields, and scalability limitations, are critically assessed. Finally, future perspectives are presented, focusing on emerging technologies such as biocatalysis, flow chemistry, C-H functionalization, electrochemical synthesis, sustainable methodologies, and artificial intelligence-assisted retrosynthetic planning, which are expected to further advance α-pyrone synthesis and facilitate drug discovery efforts.