Intercepted-Knoevenagel condensation for the synthesis of unsymmetrical fused-tricyclic 4H-pyrans

Recent advances in the multicomponent synthesis of heterocycles using tetronic acid

Tetronic acid, a versatile synthon, has been extensively investigated by numerous researchers in synthetic chemistry due to its crucial role in synthesizing heterocycles which makes this compound particularly advantageous in both pharmaceutical and biological fields. Various heterocycles can be synthesized using it as a precursor via multicomponent reactions (MCRs). Dicarbonyl groups can be considered the building blocks and key structural motifs of a wide range of natural compounds, which may contain different functional groups in the synthesis of heterocyclic frameworks. This review covers the literature from 2017 to 2022, and it encompasses the different one-pot protocols for synthesizing a variety of heterocyclic molecules.

Recent advances in the synthesis of naturally occurring tetronic acids

During the last decades the interest towards natural products containing the tetronic acid moiety augmented significantly, due to their challenging structures and to the wide range of biological activities they display. This increasing enthusiasm has led to noteworthy advances in the development of innovative methodologies for the construction of the butenolide nucleus. This review provides an overview of the progress in the synthesis of tetronic acid as a structural key motif of natural compounds, covering the last 15 years. Herein, the most representative synthetic pathways towards structurally diverse natural tetronic acids are grouped according to the strategy followed. The first part describes the functionalization of a preformed tetronic acid core by intermolecular reactions (cross-coupling reactions, nucleophilic substitution, multicomponent reactions) whereas the second part deals with intramolecular approaches (Dieckmann, cycloaddition or ring expansion reactions) to construct the heterocyclic core. This rational subcategorization allowed us to make some considerations about the best approaches for the synthesis of specific substrates, including modern intriguing methodologies such as microwave irradiation, solid phase anchoring, bio-transformations and continuous flow processes.

Strategies for the synthesis of furo-pyranones and their application in the total synthesis of related natural products

The furo-pyranone framework is widely present in the molecular structure of various biologically potent natural products and un-natural small molecules, and it represents a valuable target in synthetic organic chemistry and medicinal chemistry.