Dimethyl Sulfide → 1-Ethyl-4-(5-hexenyl)-2-oxocyclohexaneacetic Acid Methyl Ester

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Reaktionsschritte

A solution of 1-ethyl-2-oxocyclohex-3-eneacetic acid methyl ester (25 g, 127.6 mmol), CuBr.Me2S (2.62 g, 12.8 mmol) and Me2S (25.5 mL) in 375 mL of tetrahydrofuran was cooled to -40° C. under nitrogen and treated dropwise with H2C=CHCH2CH2CH2CH2MgBr (166.6 mmol, 303 mL of a 0.55M solution in tetrahydrofuran). Fifteen minutes after the addition, the reaction mixture was quenched with 300 mL of 1M HCl and extracted with 4×120 mL of ether. Drying (MgSO4), concentration in vacuo and flash chromatography (114 mm diameter column, 10% ethyl acetate in petroleum ether eluent) afforded the oily product (29.51 g, 105.4 mmol, 83%) as a mixture of diastereomers. A portion of the diastereomers was separated by preparative HPLC affording 2.25 g of isomer A, the higher Rf material, as a yellow oil.

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