Total Syntheses and Cytotoxic Evaluations of Cryptolactones A 1 , A 2 , B 1 , B 2 , and Their Derivatives.

The cryptolactones A(1), A(2), B-1, and B-2 isolated from a Cryptomyzus sp. aphid were synthesized via the Mukaiyama aldol reaction and olefin metathesis. Their antipodes and derivatives were also synthesized by the same strategy to investigate structure-activity relationships. These compounds exhibited cytotoxic activity against human promyelocytic leukemia HL-60 cells with IC50 values of 2.1-42 mu M.