Diisopropylamine → Ethyl 1-(3-(tert-butoxy)-3-oxopropanoyl)cyclopropane-1-carboxylate

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Reaction Conditions

Reaction Steps

A solution of n-butyllithium (2.5M in hexane, 40 ml) was added dropwise with stirring to a cooled solution of diisopropylamine (10.1 g) in anhydrous ether (100 ml) in an atmosphere of nitrogen, whilst maintaining the temperature below -70° C. The mixture was stirred at -78° C. for 0.5 hour and a solution of t-butyl acetate (11.6 g) in anhydrous ether (20 ml) was added dropwise, whilst maintaining the temperature below -70° C. The mixture was stirred at -78° C. for 1 hour and a solution of diethyl cyclopropane-1,1-dicarboxylate (18.6 g) in anhydrous ether (20 ml) was added dropwise whilst maintaining the temperature below -70° C. The mixture was stirred at -78° C. for 0.5 hour and the temperature was allowed to rise to room temperature. A saturated solution of ammonium chloride (150 ml) was added cautiously and the layers were separated. The organic extract was washed with water (2×50 ml) hydrochloric acid (2M, 2×50 ml) and water (2×50 ml). The solution was dried (anhydrous sodium sulphate) and filtered. The filtrate was evaporated to dryness and the residue was distilled to give t-butyl 3-(1-ethoxycarbonylcyclopropyl)-3-oxopropionate (11.66 g) as a clear oil bp 89°-90° C./0.5 mmHg.

Provenance & Evidence