Reaction Steps
A solution of 1-(tetrahydropyran-2-yloxy)-3-butyne (2.25 g, 14 mmol) in dry THF (15 ml) was treated at -50° C. with n-butyllithium hexane solution (11 ml, 17.5 mmol). After 15 min at -30° C., the mixture was kept at room temperature for 30 min. The mixture was then treated at 0° C. with 5 (3.0 g, 13.8 mmol) dissolved in 1,3-dimethyl-3,4,5,6-tetrahydro-2 (1H)-pyrimidine (DMPU) (15 mL) during 30 min. The reaction mixture was stirred 12 hr. at room temperature and quenched with saturated NH4Cl solution (30 ml). The product (6) was removed with ether (3×50 ml) and purified by silica-gel flash chromatography (2.2 g, 55% yield). 1H NMR (200 MHz) δ5.36 (m, 4H, CH=CH), 4.64 (m, 1H, CH-2'), 3.81 (m, 2H, CH2 -6' and 1), 3.54 (m, 2H, CH2 -6' and 1), 2.78 (dd, J=6.0, 6.0 Hz, 2H, =CH--CH2 --CH=), 2.47 (m, 4H, CH2 -2, and -5), 2.15 (m, 4H, CH2 -7, and -13), 1.8-1.4 (m, 8H, CH2 -6, -3', -4', and -5'), 0.96 (t, J=7.5, 7.6 Hz, 3H, CH3). 13C NMR (100.6 MHz) δ: 131.8 (12), 128.9 (9, 11), 127.2 (8), 98.7 (2'), 81.0 (3), 76.6 (4), 66.2 (1), 62.2 (6'), 33.4 (2), 30.6 (3'), 28.9 (7), 26.2 (6), 25.5 (14), 25.4 (4'), 20.5 (5), 20.2 (13), 18.3 (5'), 14.3 (10). MS [EI, m/z (%)] 159 (7), 131 (9), 119 (8), 117 (9), 105 (8), 93 (11), 91 (16), 86 (12), 85 (100), 79 (18), 77 (11), 67 (36), 57 (16), 55 (15), 43 (29), 42 (16), 41 (51), 40 (24).
