Hydrochloric Acid → t-Butyl 3-(1-methylcyclopropyl)-3-oxopropionate

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A solution of n-butyllithium (2.5M in hexane, 36 ml) was added dropwise with stirring to a cooled solution of diisopropylamine (9.09 g) in dry tetrahydrofuran (i.e. tetrahydofuran) in an atmosphere of nitrogen, whilst maintaining the temperature below -70° C. The mixture was stirred for 0.25 hour and t-butyltrimethylsilylacetate (16.9 g) was added dropwise with stirring whilst maintaining the temperature below -70° C. The mixture was stirred at -78° C. for 1 hour. A suspension of 1-(1-methylcyclopropylcarbonyl)-imidazole (13.5 g) in dry tetrahydrofuran (120 ml) was added dropwise whilst maintaining the temperature below -60° C. The mixture was stirred at -78° C. for 3 hours and the temperature was allowed to rise to room temperature. Hydrochloric acid (2M, 100 ml) was added cautiously and the mixture was extracted with ether (2×100 ml). The combined extracts were washed with hydrochloric acid (2M, 3×50 ml) and water (3×50 ml), dried (anhydrous sodium sulphate) and filtered. The filtrate was evaporated to dryness to give t-butyl 3-(1-methylcyclopropyl)-3-oxopropionate as an orange oil NMR (CDCl3) 0.65(m,2H), 1.1(m,2H), 1.25(s,3H), 1.4(s,9H), 3.2(s,2H).

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