Reaction Steps
A round bottom flask was charged with LiCl (66.6 mg, 1.57 mmol) and flamed dried under vacuum. Pd(PPh3)4 (32.6 mg, 0.026 mmol), CuCl (129.6 mg, 1.31 mmol) and DMSO (2.0 mL) were added and the mixture was degassed. 3a (100 mg, 0.262 mmol) was added, followed by ethyl (E)-3-(tri-n-butylstannyl)-2-pentenoate (131.4 mg, 0.314 mmol) and the resulting mixture was degassed. See Piers, E., et al., Can. J. Chem., 2058 (1992). The reaction mixture was then heated at 60° C. for 17 h. After cooling, the reaction was diluted with Et2O (30 mL) and washed with a mixture of brine (40 mL) and 5% aq. NH4OH (8 mL). The aqueous layer was extracted 3 times with Et2O. The combined organic extracts were dried over MgSO4 and concentrated under reduced pressure. The crude product was purified by flash chromatography (gradient hexane to hexane-EtOAc 95:5) to yield 4a (80 mg, 80%) as a clear oil. 1H NMR (300 MHz, CDCl3) δ0.28 (s, 3H), 0.99 (t, J=7.5 Hz, 3H), 1.3 (t, J=7.1 Hz, 3H), 2.98 (q, J=7.5 Hz, 2H), 3.42 (s, 3H), 4.02 (s, 3H), 4.2 (q, J=7.1 Hz, 2H), 4.47 (s, 2H), 4.72 (s, 2H), 5.79 (s, 1H), 6.84 (s, 1H); 13C NMR (75 MHz, CDCl3) δ−1.96, 12.3, 14.25, 26.57, 53.58, 55.35, 60.01, 61.95, 9672, 115.49, 119.49, 121.17, 151.15, 159.9, 162.21, 164.81, 165.83; IR (film, NaCl, cm−1) 2; LRMS (70 eV, EI) m/z (rel int %) 381 (M+), 366, 336, 320, 308 (100), 290, 262, 246, 89, 73. HRMS m/z calcd for C19H31NO5Si (M+) 381.1976, found 381.19667.
