The absolute configurations of angelols A-H (1-8) isolated from Angelica pubescens MAXIM. (Umbelliferae) were determined to be as shown in Chart 1 by means of chemical, spectral and X-ray analysis. Furthermore, the stereostructure of angelol B (2) was determined to be as shown in Fig. 1 on the basis of X-ray analysis.
followed by bromine–iodine exchange and Pd–Cu co-catalyzed Stille cross-coupling of the resulting alkenyl iodide with methyl (Z)-2-tributylstannyl-3-methoxyacrylate (7). The synthetic strobilurins G, M, and N were identical with the corresponding natural compounds. In addition, the (2′ S)-configuration of strobilurin G (1) was unambiguously established by oxidative degradation of the synthetic intermediate