Isolation and Total Syntheses of Cytotoxic Cryptolactones A<sub>1</sub>, A<sub>2</sub>, B<sub>1</sub>, and B<sub>2</sub>: α,β-Unsaturated δ-Lactones from a <i>Cryptomyzus</i> sp. Aphid
The cryptolactones A1, A2, B1, and B2, which are α,β-unsaturatedδ-lactones, were isolated from a Cryptomyzus sp. aphid. The structures were established by 1-D and 2-D NMR spectra and CI-HRMS. Their absolute configurations were determined with the Kusumi–Mosher method, combined with asymmetric total syntheses. The syntheses were accomplished with the Mukaiyama aldol reaction and olefin metathesis,
Total Syntheses and Cytotoxic Evaluations of Cryptolactones A<sub>1</sub>, A<sub>2</sub>, B<sub>1</sub>, B<sub>2</sub>, and Their Derivatives
The cryptolactones A1, A2, B1, and B2 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 µM.
perfluoroalkyl iodides with silyl enol ethers mediated by Et3B in the presence of base such as 2,6-dimethylpyridine provides mixtures of perfluoroalkylated trialkylsilyl enol ethers and α-perfluoroalkylated ketones. The yield and distribution of the products heavily depend on the nature of base employed. Treatment of a reaction mixture consisting of perfluoroalkylated silyl enol ether and α-perfluoroalkylated
Treatment of tertiary cyclopropyl silyl ethers with diethylaminosulfur trifluoride (DAST) causes ring opening to give allylic fluorides in moderate to high yields.