-Lactones and -lactams are found in numerous agrochemicals, pharmaceuticals and bioactive natural products (Scheme 1A). For example, spironolactone (1a) is used to treat heart failure, strigol (1b) inhibits plant-shoots branching and nirmatrelvir (1c) is used for the treatment of COVID-19. Hence, various synthetic approaches have been developed over the years to construct lactones, mainly focusing on the formation of CO bonds (Scheme 1B). Esterification of 1,4-hydroxy acids, Baeyer-Villiger oxidation and cyclization of carboxylic acids onto olefins are among the most frequently used methods. In contrast, the synthesis of -lactones and -lactams via C-C bond formation has been less investigated, although it has potential for a more convergent construction of the carbon backbone of the molecules. Radical-based approaches are especially attractive due to their high functional group tolerance, mild reaction conditions and lower sensibility towards steric hindrance. In particular, the 5-exo-trig cyclization of an alkoxycarbonyl radical onto an olefin is an attractive strategy as the radical precursor can be generated from easily accessible homoallylic alcohols and the radical generated after cyclization can be trapped by a SOMOphile, hence allowing multi-functionalization reactions (Scheme 1C). In this regard, lactonization has been reported using selenocarbonates, N-alkoxyoxalyloxy-2-thiopyridones and S-alkoxycarbonyl xanthates under classical conditions for the generation of radicals. The formed alkyl radicals were then trapped by a hydrogen atom, a thiopyridine or a xanthate moiety, with only one example of double CC bond formation in a 5-exotrig -Giese addition sequence. More recently, Overman and coworkers reported the synthesis of arylated and vinylated spirolactones via a photoredox-catalyzed alkoxycarbonyl radical cyclization -Ni-catalyzed cross-coupling cascade using easily accessible homoallylic cesium oxalates as substrates and an iridium photocatalyst (Scheme 1D). Scheme 1. Lactones and Lactams: importance in pharmaceutical and agrochemical industries (A) and synthetic strategies (B-E).