Hexamethylphosphoramide → Lithium cyclohexylisopropylamide

Beteiligte Stoffe

Reaktionsschritte

Lithium cyclohexylisopropylamide was prepared from cyclohexylisopropylamine (0.07 ml) and n-butyllithium (1.6-M, 0.265 ml) in THF (1 ml). To the resultant was added dropwise a solution of methyl ester (34) (0.1412 g) in THF (4 ml) and stirred for 2 hours. A solution of diphenyl diselenide (0.132 g) and HMPA (0.074 ml) in THF (2 ml) was added, and the mixture was stirred at -70° C. for one hour and -40° C.--30° C. for 1.5 hours. According to the conventional treatment, selenide (35) (0.1247 g) was obtained. Selenide (35) (0.1247 g) was dissolved in ethyl acetate (6 ml) and methanol (4 ml), and stirred at room temperature with aqueous hydrogen peroxide (30%) (0.5 ml) for one hour. The crude product obtained by the conventional treatment was chromatographed (ethyl acetate/hexane (1:6)) to give Δ2 -PGE2 α-methyl ester (36). Yield, 0.091 g.

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