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

alpha-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 alpha-angelica lactone over the last years. Beyond its upgrading to added value products, such as gamma-valerolactone, polymers, and biofuels, alpha-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. alpha-Angelica lactone proved to be a versatile scaffold in stereoselective vinylogous 1,4- and 1,2-addition, cycloaddition, isomerization, gamma-arylation, and reduction reactions.