Propargyl bromide → 5-Hydroxy-7-propargyloxy-2,2-dimethyl-4-chromanone

Participants

Reaction Conditions

Reaction Steps

In 60 ml of methyl-ethyl-ketone 4.2 g of 5,7-dihydroxy-2,2-dimethyl-4-chromanone are dissolved, whereupon 3.0 g (22 millimoles) of potassium carbonate, 0.2 g of potassium iodide, and 3.0 g (2.3 ml, 25 millimoles) of propargyl bromide are added and the reaction mixture is refluxed for 4 hours. The inorganic salt is filtered off, the residue is taken up in 100 ml of carbon tetrachloride and extracted twice with 25 ml of a 5% sodium hydroxide solution each. The aqueous-alkaline layer is cooled to 0° C. The precipitated sodium phenolate salt is filtered off, washed twice with 20 ml of acetone each, and suspended in 25% hydrochloric acid (50 ml). The mixture is stirred at 5° C. for an hour. The precipitated white product is filtered off, washed twice with 20 ml of water each and dried to constant weight. The crude product thus obtained can be directly subjected to further reactions. Thus 3.7 g of the desired compound are obtained, yield 75%, Mp.: 122°-124° C.

Provenance & Evidence