766-97-2

A magnetically stirred [Pd(PPh3)2Cl2] (0.02 mmol; 14 mg), CuI (0.04 mmol; 7.6 mg), and bromine substrate (1 mmol) were placed in an oven-dried screw-cap reaction tube. Anhydrous THF (1 mL) was then added under nitrogen atmosphere with stirring at room temperature, followed by triethylamine (1.55 mmol; 216 μL). Trimethylsilylacetylene (1.25 mmol; 176 μL) was slowly added to the reaction mixture under nitrogen atmosphere. The reaction gradually darkened. The reaction mixture was continuously stirred at room temperature for 24 hours. The reaction was monitored by TLC. Once the reaction was complete, the mixture was diluted with 5 mL of EtOAc and filtered through diatomaceous earth. The filtrate was evaporated under reduced pressure, and the compounds were separated by silica gel column chromatography (100-200 mesh). The terminal alkyne was then obtained by hydrolysis of the 4-(trimethylsilyl)acetylene substrate.

Figure 4-Ethynyltoluene Synthetic Route