Configurational and Conformational Analysis of Macrocarpals H, I, and J from Eucalyptus globulus.

Abstract

Configurational and conformational analysis of unique phloroglucinol-sesquiterpene coupled compounds, macrocarpals H, I, and J (1-3), showing potent antibacterial activity and inhibitory effect of glucosyltransferase, was made by nuclear Overhauser enhancement (NOE) experiments and computational chemical methods. The configuration at C-9' of the side chains of 1-3 was elucidated as 1: S, 2: R, and 3: S, by the structures obtained by the Monte Carlo (MC) calculation using MM2* force field implemented in MacroModel/Batchmin, followed by semiempirical molecular orbital calculations, whose stable conformation of macrocarpals H, I, and J was well satisfied by the NOEs observed around H-9'.