Trimethylaluminum → 5-(2-diethylamino-ethyl)-3-methyl-4-oxo-4,5,6,7,8,9-hexahydro-1H-1,5-diaza-cyclopentacyclooctene-2-carbaldehyde

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Reaction Steps

Trimethyl aluminum (489 μl, 2 mol/L) was dissolved in 3 ml of toluene under stirring, and added with the solution of 5-(4-diethylamino-butyl)-3-methyl-1H-pyrrole-2,4-dicarboxylic acid 2-tert-butyl ester 4-ethyl ester 60d (345 mg, 0.82 mmol) in 6 ml of toluene to the above solution at room temperature. Upon completion of the addition, the reaction mixture was stirred for 30 minutes at room temperature, heated to reflux for 2 hours in an oil bath, added with another trimethyl aluminum (900 μl, 2 mol/L) and refluxed for another 7 hours. After thin lay chromatography showed the disappearance of starting materials, the reaction mixture was quenched with water, added with hydrochloric acid solution (1 ml, 2 mol/L) and stirred for 30 minutes at room temperature. The mixture was adjusted to about pH 10 with aqueous sodium hydroxide solution (10%) and extracted with ethyl acetate (25 ml×3). The combined organic extracts were washed with saturated brine (25 ml), dried over anhydrous magnesium sulfate, filtered to remove the drying agent and concentrated under reduced pressure. The residue was purified by silica gel column chromatography to obtain the title compound 5-(2-diethylamino-ethyl)-3-methyl-4-oxo-4,5,6,7,8,9-hexahydro-1H-1,5-diaza-cyclopentacyclooctene-2-carbaldehyde 60e (60 mg, yield 26.7%) as a white solid.

Provenance & Evidence