Ethyl Acetate → 1-(t-Butoxycarbonyl)-4-(2-tributylstannylethyn-1-yl)piperidine

Participants

Reaction Steps

A mixture of 23.199 g (62.85 mmole) 1-(t-butoxycarbonyl)-4-(2,2-dibromoethen-1-yl)-piperidine (prepared as in Step 3 above) and 600 mL anhydrous THF was cooled with dry ice acetone bath under nitrogen. To this mixture was added 88 mL of a 1.6 M BuLi solution in hexanes dropwise with stirring and cooling over 50 minutes. After one hour, the flask was transferred into an ice bath. After another hour, a solution of 28.64 g (87.99 mmole) tributyltin chloride in 100 mL THF was added with stirring and cooling over 35 minutes. After three hours, the mixture was concentrated under vacuum to remove some THF, and the residue was partitioned between 600 mL ice water and 800 mL ether. The organic layer was washed with 200 mL of water (1×), 2% NaHCO3 (1×), water (2×), and saturated brine (1×), dried over Na2SO4 and concentrated under vacuum to give 30.104 g crude product as a green-yellowish liquid. FC on 275 g silica gel using cold 2.5-15% EtOAc in hexanes as quickly as possible to give 27.115 g title compound as a colorless liquid. RF: 0.45 (10% EtOAc in hexanes); H NMR (500 MHz) δ 3.63-3.67 (m, 2H), 3.25-3.30 (m, 2H), 2.64-2.69 (m, 1H), 1.74-1.79 (m, 2H), 1.54-1.64 (m, 8H), 1.47 (s, 9H), 1.32-1.39 (m, 6H), 0.96-0.99 (m, 6H), 0.92 (t, J=7.3 Hz, 9H).

Provenance & Evidence