N,N,N',N'-Tetramethylethylenediamine → 1,2,3,3a,8,8a-Hexahydro-alpha-oxo-1,3a,8-trimethyl-5-pyrrolo[2,3-b]indole acetic acid, diisopropyl amide

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a solution of TMEDA (2.85 ml) in anhydrous ether (5.0 ml) was added at -78° C. under N2 atmosphere, sec-butyllithium (14.5 ml). The resulting solution was subsequently treated with a solution of 5-bromo-1,2,3,3a,8,8a-hexahydro-1,3a,8-trimethylpyrrolo[2,3-b]indole (3.80 g) in anhydrous ether (10 ml). The mixture was held at this temperature for 3 hours and then added to a solution of diisopropylamino-oxo-acetic acid, ethyl ester (7.5 g) in anhydrous ether (15 ml). After stirring at -78° C. for 4 hours, the reaction mixture was quenched with 50 ml of aqueous NH4Cl solution. The organic and aqueous phases were separated and the organic phase washed successively with saturated aqueous NaHCO3 and brine. The organic phase was dried (Na2SO4), filtered and concentrated to an oil which was purified by HPLC (silica gel, 10% MeOH in ethyl acetate as eluent). 2.8 g of 1,2,3,3a,8,8a-Hexahydro-α-oxo- 1,3a,8-trimethyl-5-pyrrolo[2,3-b]indole acetic acid, diisopropyl amide was obtained as a foam. Trituration with hexane and drying under reduced pressure yielded an analytically pure sample.

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