41658-03-1

1. Synthesis of ethyl 3-bromopropiolate Silver nitrite (1.72 g, 10.2 mmol, 0.1 eq.) was slowly added to a solution of ethyl propiolate (10.00 g, 102 mmol, 1.0 eq.) in acetone (200 mL) at room temperature. After stirring the reaction mixture for 5 min, N-bromosuccinimide (NBS, 20.0 g, 112 mmol, 1.1 eq.) was added and the reaction continued to be stirred for 2 h at room temperature. The reaction progression was monitored by thin layer chromatography (TLC) (unfolding agent: 5% ethyl acetate-hexane, Rf = 0.55). After completion of the reaction, the reaction mixture was filtered through a diatomaceous earth pad and washed with acetone. The filtrate was collected and concentrated under reduced pressure at 25-30 °C to give ethyl 3-bromopropiolate crude as an oil.

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