Organo‐, Metal‐, and Enzyme‐Mediated Stereoselective Transformations of α‐Angelica Lactone

Abstract α‐Angelica lactone is a five‐membered heterocycle belonging to the rich family of butenolides, a key motif, present in a great variety of bioactive and natural products. Moreover, it is a small compound attainable from the platform molecule levulinic acid, which in turn is readily accessible from lignocellulosic biomass. These important features contributed to arousing interest in α‐angelica lactone over the last years. Beyond its upgrading to added value products, such as γ‐valerolactone, polymers, and biofuels, α‐angelica lactone has been identified as a building block in natural product synthesis and a useful reagent in asymmetric catalysis. In this minireview, we provide an overview of diastereo‐ and enantioselective organo‐, metal‐, and enzymatic approaches reported from 2020 up to 2024, where this heterocycle has been used as the starting material. α‐Angelica lactone proved to be a versatile scaffold in stereoselective vinylogous 1,4‐ and 1,2‐addition, cycloaddition, isomerization, γ‐arylation, and reduction reactions.