Propargyl bromide → 2-(1,1-Dimethylethyl)-2,4-dihydro-5-phenyl-4-(2-propyn-1-yl)-3H-1,2,4-triazol-3-one

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Reaction Steps

A mixture of crude 345 g (1.2 mol) of 1-t-butyl-4-H-3-phenyl-1,2,4-triazol-5-one and 3.5 L of ethyl acetate containing 0.03% water was stirred at room temperature and 190 g (1.67 mol) of solid potassium carbonate (K2CO3) was added. The mixture was heated at reflux for 0.5 h and 248 g (1.67 mol) of an 80% weight solution of propargyl bromide in toluene was added dropwise over 30 minutes. Refluxing was continued for an additional 3 h. The mixture was allowed to cool to room temperature, diluted with 2 L of water and stirred for 15 min. The organic layer was separated, washed with brine and dried over magnesium sulfate (MgSO4). Removal of the solvent left 300 g of an oil which was crystallized from 500 mL of ether and 1500 mL of hexanes to furnish 180 g of the desired compound, mp 82°-83° C.

Provenance & Evidence