To a solution of 1 mol 2-(4-Chloro-phenyl)-N-[2-(4-hydroxy-3-methoxy-phenyl)-ethyl]-2-prop-2-ynyloxyacetamide in 500 ml toluene, 207 g potassium carbonate (1.5 mole) and 10 g tetrabutylammonium bromide are added. The mixture is heated to 90° C. and 1.4 mole propargyl chloride as a 35% solution in toluene is added over 30 minutes. After 3 hours the conversion of 2-(4-Chloro-phenyl)-N-[2-(4-hydroxy-3-methoxy-phenyl)-ethyl]-2-prop-2-ynyloxyacetamide is complete. To dissolve the salts 500 ml water are added and separated from the toluene product phase. The toluene is completely evaporated at 80° C./20 mbar and replaced by methanol. The product 2-(4-Chloro-phenyl)-N-[2-(3-methoxy-4-prop-2-ynyloxy-phenyl)-ethyl]-2-prop-2-ynyloxyacetamide is crystallized from solution by cooling down to 0° C., filtered and washed with 200 ml methanol of 0° C. The product is dried at 50° C. under vacuum. 315 g of 2-(4-Chloro-phenyl)-N-[2-(3-methoxy-4-prop-2-ynyloxy-phenyl)-ethyl]-2-prop-2-ynyloxyacetamide are obtained with a LC purity of 98%. Melting point=94-96° C.
