Structural Elucidation and Computational Study of Limonoids fromChisocheton Erythrocarpus (Meliaceae)

摘要

closely related families in the order Rutales such as Rutaceae, Simaroubaceae, Cneoraceae, and Meliaceae. Among them,Meliaceae family produces the most variety of limonoid skeletons. Biosynthetically, limonoids are derived from triterpenes byhaving lost four carbon atoms in the final product. Hence they are formally known as tetranortriterpenoids. Structuralelucidations were based on spectroscopic methods; NMR, UV, IR, and mass spectrometry. The absolute stereochemistry ofsome new and novel limonoids will be discussed. In order to determine the absolute configuration of limonoids, we employedthe most widely used chiroptical technique; electronic circular dichroism (ECD). For optically active organic compound, it is anexcellent tool for probing the chirality of chromophores through CD cotton effect, from which the determination of the absoluteconfiguration can be achieved. Along with the experimental results, the simulation of CD curves using density functionaltheory (DFT) calculations was provided to compare and verify the assigned absolute configurations of new limonoids.