[H-].[Na+].[Br-].[CH2:4]([P+](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)[C:5]1[CH:10]=[CH:9][CH:8]=[CH:7][CH:6]=1.[O:30]1[C:34]2([CH2:39][CH2:38][C:37](=O)[CH2:36][CH2:35]2)[O:33][CH2:32][CH2:31]1>CS(C)=O>[CH:4](=[C:37]1[CH2:38][CH2:39][C:34]2([O:33][CH2:32][CH2:31][O:30]2)[CH2:35][CH2:36]1)[C:5]1[CH:10]=[CH:9][CH:8]=[CH:7][CH:6]=1To a suspension of NaH (0.306 g, 12.8 mmol) in DMSO (10 mL), a solution of benzyl-triphenylphosphonium bromide (5.44 g, 12.8 mmol) in DMSO (30 mL) was slowly added at rt. The solution was stirred 30 min at rt and then further 30 min at 50° C. Upon the crude mixture turning into dark red color, a solution of 1,4-dioxaspiro[4.5]decan-8-one (2.0 g, 12.8 mmol) in DMSO (14 mL) was added. The solution was stirred at 50° C. for 16 h. The reaction mixture was quenched with water and the aqueous layer extracted with AcOEt (3×20 mL). The combined organic layers were washed with brine, dried over Na2SO4, filtered and concentrated to dryness to give a crude product, which was purified by column chromatography using a Teledyne ISCO apparatus, eluting with Cy/AcOEt (from 100:0 to 40:60) to afford the title compound (1.8 g, 61%) as a white solid. 1H NMR (CDCl3): δ 1.66-1.73 (m, 2H), 1.77-1.84 (m, 2H), 2.40-2.47 (m, 2H), 2.49-2.57 (m, 2H), 3.99 (s, 4H), 6.31 (s, 1H), 7.17-7.23 (m, 3H), 7.28-7.35 (m, 2H).
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