A 1 dram vial equipped with a stir bar is charged with 12.6 mg (0.031 mmol, 1 equiv.) of starting material 50 followed by 660 μL of THF. The solution is cooled to −78° C. prior to the addition of 124 μL of LDA (0.50 M, 0.062 mmol, 2 equiv.). The mixture was then stirred for 20 minutes followed by the addition of 18 μL (0.155 mmol, 5 equiv.) of prenyl bromide. Stirring was continued for an additional 20 minutes at which time the reaction was quenched by the addition of 500 μL of saturated aqueous ammonium chloride. The reaction was transferred to a separatory funnel in diethyl ether, and the organic layer was washed twice with water, dried with MgSO4, and concentrated in vacuo. The crude product was purified by silica gel chromatography (Rf=0.25 in 9:1 hexane:ethyl acetate), affording 7.5 mg (51% yield) of 54 as a clear oil. 1H NMR (500 MHz, CDCl3) δ ppm 5.07 (t, J=7.0 Hz, 1H), 5.04-4.94 (m, 2H), 4.58 (dd, J=7.0, 47.1 Hz, 2H), 3.95 (s, 3H), 3.60 (dd, J=5.3, 11.4 Hz, 1H), 3.33 (s, 3H), 3.25 (s, 1H), 3.13 (d, J=6.4 Hz, 2H), 2.50 (dd, J=6.2, 14.7 Hz, 1H), 2.42-2.28 (m, 2H), 2.25 (dd, J=5.2, 13.4 Hz, 1H), 1.96-1.84 (m, 1H), 1.77 (dd, J=11.5, 13.3 Hz, 1H), 1.71-1.61 (m, 18H), 1.58-1.51 (m, 2H), 1.30-1.23 (m, 2H), 1.18 (dt, J=4.3, 12.8 Hz, 2H), 0.91 (s, 3H). HRMS-ESI (m/z): [M+H]+ calculated for C29H44O5, 473.3262. found 473.3250.
