General method: 3-ethynylpyridine (1.0 mmol) was added to a 10 mL Schlenk tube equipped with a magnetic stirrer to which HSi(OEt)2Me (5.0 mmol) and KOtBu (1.5 mmol) had been pre-filled. The Schlenk tube was evacuated and backfilled with CO2, and this process was repeated three times. After connecting the CO2 gas bladder, the reactor was transferred to a water bath at 40 °C. After the reaction mixture was reacted under stirring conditions for 2 h, it was diluted with water (30 mL) and extracted with dichloromethane (3 × 10 mL). The aqueous layer was acidified with 6 M HCl aqueous solution and then extracted with diethyl ether (5 x 20 mL). The organic extracts were combined, dried with anhydrous Na2SO4 and subsequently concentrated under vacuum to give pure 3-(pyridin-3-yl)propargyl acid (as compound 3a, yield: 98%).
