[CH3:1]P(=O)(OCC)OCC.O1CCCC1.C([Li])CCC.[CH:20](=[C:27]1[C:36]2[C:31](=[CH:32][CH:33]=[CH:34][CH:35]=2)[C:29](=[O:30])O1)[C:21]1[CH:26]=[CH:25][CH:24]=[CH:23][CH:22]=1>CCCCCC.O>[CH2:20]([C:27]1[C:36]2[C:31](=[CH:32][CH:33]=[CH:34][CH:35]=2)[C:29](=[O:30])[CH:1]=1)[C:21]1[CH:22]=[CH:23][CH:24]=[CH:25][CH:26]=1Diethyl methylphosphonate (1.94 g.) suspended in 50 ml. of dry tetrahydrofuran is treated with 1.1 equivalents of butyl lithium in hexane under nitrogen at about -78°. After 10 minutes, one equivalent of benzalphthalide in 10 ml. of tetrahydrofuran is added while maintaining the temperature at about -78°. The reaction mixture is allowed to warm to room temperature and then left to stand at room temperature for 3 hours. The reaction mixture is diluted with water and then extracted with ether. The ether extracts are combined, washed with water, dried and the solvent removed under vacuum. The residue is chromatographed on silica eluting with methylene chloride:hexane (4:1) to afford 3-benzylind-2-en-1-one and a small amount of starting material.
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