[O:1]1[C:6]2[CH:7]=[CH:8][CH:9]=[CH:10][C:5]=2[O:4][CH2:3][CH:2]1[CH2:11][OH:12].[CH2:13]([O:15][C:16](=[O:20])[C:17]#[C:18][CH3:19])[CH3:14].C(P(CCCC)CCCC)CCC>O1CCCC1>[CH2:13]([O:15][C:16](=[O:20])/[CH:17]=[C:18](/[O:12][CH2:11][CH:2]1[O:1][C:6]2[CH:7]=[CH:8][CH:9]=[CH:10][C:5]=2[O:4][CH2:3]1)\[CH3:19])[CH3:14]To a stirred mixture of (2,3-dihydro-benzo[1,4]dioxin-2-yl)-methanol (1.01 g, 5.90 mmol) and ethyl-2-butynoate (820 mg, 7.08 mmol) in tetrahydrofuran (15 mL) was added tri-n-butylphosphine (0.25 g, 1.18 mmol). The mixture was stirred at room temperature for 1.5 h. Upon completion of the reaction the tetrahydrofuran was removed in vacuo. The crude product obtained was purified by ISCO flash chromatography (Teledyne Isco RediSep Flash Column 40 g; 0% to 50% ethyl acetate/hexanes) to afford (E)-3-(2,3-dihydro-benzo[1,4]dioxin-2-ylmethoxy)-but-2-enoic acid ethyl ester (660 mg, 40%) as a colorless oil: LR-ES-MS m/z calculated for C15H18O5 [M]+ 278, observed [M+H]+ 279.
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