Synthesis of andrographolide-related esters as insecticidal and acaricidal agents

Abstract In continuation of our program aimed at the development of natural product-based pesticidal agents, a series of andrographolide-related esters, such as 3,19-dialkyl(aryl)carbonyloxy andrographolide ( 3a – g ), 3-alkyl(aryl)carbonyloxyandrographolide ( 4a – g ), and 19-alkyl(aryl)carbonyloxyandrographolide ( 5a – g ), were prepared. Their structures were well characterized by 1 H NMR, IR, optical rotation, HRMS and mp. Especially three-dimensional structures of compounds 3a , 4g , and 5g were unambiguously confirmed by single-crystal X-ray diffraction. Compounds 3a and 5a exhibited good insecticidal and acaricidal activities against Mythimna separata and Tetranychus cinnabarinus . Their structure-activity relationships were also discussed.