To a solution of 24 (38 mg, 0.12 mmol) in THF (2 mL) at -78 °C was added LDA (2.0 mL, 0.13 M). After 5 min a solution of N-formylimidazole (0.75 mL, 0.53 M in THF, 0.40 mmol) was added to the orange reaction mixture. The orange color immediately dissipated. The reaction was allowed to warm to ambient temperature over 35 min. The reaction was partitioned between 5% HC1 (3 mL) and ether (5 mL). The aqueous fraction was extracted with 5 mL of ether and the combined organic fractions were dried with MgS04 and concentrated in vacuo. The residue was combined with K2C03 (30 mg, 0.22 mmol) and dimethyl sulfate (0.125 mL, 1.32 mmol) in 4 mL of acetone. After 12 h the reaction was diluted with ether (5 mL), washed with water (5 mL), dried (MgS04), and concentrated in vacuo. The residue was chromatographed on silica gel (15:1 hexane/ethyl acetate) to yield (±)-oudemansin B (19 mg, 44%) as a clear oil, in addition to recovered 24 (5 mg). 2: IR (neat oil) 1700, 1640, 1080 cm"1;
The 1,3‐diketones (I) are selectively fluorinated to give the monofluoro diones (IV) by treatment of the corresponding silyl enol ethers (III) with diluted fluorine in nitrogen.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.