Ethyl Acetate → Japonilure

Participants

Reaction Steps

In an argon atmosphere, 10 ml of anhydrous tetrahydrofuran were added to 570 mg (3.0 mmol) of purified copper iodide (CuI) and 318 mg (7.5 mmol) of lithium chloride (LiCl) dried at a reduced pressure and 130° C., and the resultant solution was stirred at room temperature for about 30 minutes. The resultant transparent solution was cooled to about -60° C., a solution obtained by dissolving 336 mg (1.511 mmol) of the compound (17) obtained in step h in 3.5 ml of tetrahydrofuran was added to the above transparent solution, and 0.81 ml (6 mmol) of chlorotrimethylsilane chloride immediate after distillation were added to the above solution. The resultant mixture was stirred for 10 minutes, and 1.5 ml (5.5 mmol) of distilled and purified n-Bu3SnH were added thereto in a small amount each time over 5 minutes. Thereafter, cooling was stopped, and the temperature of the reaction solution was raised to 0° C. at room temperature over about 30 minutes. 20 ml of a 10% aqueous potassium fluoride solution were added to this reaction solution, and the mixture was stirred. The produced precipitate was filtered. This filtrate was extracted with tetrahydrofuran and concentrated, 30 ml of a 10% aqueous potassium fluoride solution were added to the residue, and the solution was stirred for 15 minutes. 30 ml of ether were further added to the above solution, and the resultant solution was stirred for 15 minutes. The stirred solution was filtered, the filtrate was separated, and the water layer thereof was extracted with ether. The extracted solution was collected and sequentially washed with water and brine solution and was dried with anhydrous magnesium sulfate. Then, the crude product obtained by concentrating the extracted solution was purified by chromatography using silica gel (270-400 meshes, 10 g, developing solution of hexane: ethyl acetate at a mixing ratio of 98:2 to 96:4), thereby obtaining 265 mg of a compound (18) (yield:78%). The IR and NMR spectra of the resultant compound (18) coincided with the reported data [References: Y. Nishida, et al, Agric. Biol. Chem., 51, 635 (1987) (to be referred to as reference 1 hereinafter) and R. E. Dolitle, et al, J. Chem. Ecol., 6, 473 (1980) (to be referred to as reference 2 hereinafter)]. Other physical data were as follows.

Provenance & Evidence