Reaction Steps
n-Butyllithium (1.6 M, 4.2 mL, 6.7 mmol) is added slowly to a solution of the title B compound, 3-ethylsulfanyl-5-methyl-imidazo[1,5-a]pyridine (1.14 g, 6.4 mmol) in anhydrous THF (7 mL) at −78° C. The resulting solution is stirred at −78° C. for 1 h and tributyltinchloride (2.0 mL, 7.4 mmol) is added. The reaction is stirred at −78° C. for 1 h further, and then allowed slowly to warm to RT overnight. The reaction is quenched by addition of saturated aqueous ammonium chloride (15 mL) and the mixture is extracted two times with ethyl acetate. The organic extracts are combined, washed with aqueous potassium fluoride solution (3 M, 20 mL), dried over anhydrous magnesium sulfate, filtered and concentrated. The residue is purified by flash column chromatography on silica using 10% ethyl acetate in hexanes as the eluant to yield 3-ethylsulfanyl-5-tributylstannyl-imidazo[1,5-a]pyridine as a dark oil: 1H-NMR (CDCl3) δ 7.51 (s, 1H), 7.38 (dd, J=8.7, 1.2, 1H), 6.71 (dd, J=6.3, 1.5, 1H), 6.63 (dd, J=8.7, 6.3, 1H), 2.98 (q, J=7.4, 2H), 1.58–1.48 (m, 6H), 1.40–1.17 (m, 15H), 0.88 (t, J=7.5, 9H); 13C-NMR (CDCl3) δ 140.27, 133.53, 132.20, 124.88, 124.76, 124.63, 121.89, 118.77, 118.65, 118.56, 32.22, 29.66, 29.37, 29.30, 29.22, 27.94, 27.79, 27.68, 27.42, 15.59, 15.52, 14.83, 14.12, 14.03, 12.71, 12.65; MS (M+1)+ 465, 466, 467, 468, 469 (tin isotope pattern).
