coronarin A, a labdane-type diterpene isolated from Zingiberaceae plants, was used as the starting material to synthetize diterpene derivatives. As a result, eight novel α, β-unsaturated γ-butenolide derivatives (compounds 1- 8) were synthesized via photosensitized oxidation and acylation reactions. In vitro antibacterial activities of the 8 compounds were systematically evaluated. The results showed that all compounds exhibited varying degrees of antibacterial activity. Notably, compounds 1 and 2 demonstrated exceptional activity against the Gram-negative bacterium Acinetobacter baumannii ATCC19606, with minimum inhibitory concentrations (MIC) of 1 μg/mL and 0.5 μg/mL, respectively, which were significantly stronger than the positive control drug (kanamycin, MIC = 1 μg/mL). Structure-activity relationship analysis suggested that derivatives with a 15-hydroxy-16-carbonyl unsaturated lactone derivatives(B-type derivatives) exhibited stronger antibacterial activity than those with a 15-carbonyl-16-hydroxy lactone derivatives (A-type derivatives). This study highlights that the α, β-unsaturated γ-lactone ring on the side chain and acylation at the C-7 position are critical for antibacterial activity. These findings provide a theoretical foundation for developing novel plant-derived antibacterial lead compounds.