Organoelectrochemistry-Enabled Biomimetic Syntheses of Alstoscholarinoids A and B

We report efficient electrochemically enabled syntheses of natural products alstoscholarinoids A (1) and B (2). Employing oleanolic acid (OA) as the feedstock, gram-scale syntheses of biosynthetic precursors diene 3 (under AP mode) and lactone 4 (under DC mode) were achieved. Subsequent gram-scale transformations furnished 1 and 2 through singlet oxygen-mediated oxidative rearrangement of 3 and ozonolysis of 4 followed by an aldol/lactonization cascade, respectively. This strategy delivers 1 in 36% yield over two steps and 2 in 42% yield over three steps, establishing the most concise synthetic routes to these architecturally complex triterpenoids to date.