Sharpless AD strategy towards the γ-methyl butenolide unit of acetogenins: enantioselective synthesis of butenolide I and II with mosquito larvicidal activity

A novel synthetic strategy toward the γ-methyl butenolides has been established based on Sharpless asymmetric dihydroxylation in high yields and good enantiopurity. The route could be expanded to the synthesis of α,γ-disubstituted butenolide units of naturally occurring annonaceous acetogenins. Utilizing this strategy, three simple natural products with butenolide segments were synthesized enantioselectively.