[CH:1]([C@H:3]1[C@H:10]([O:11][C:12](=[O:19])[C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)[CH2:9][C@H:8]2[C@@H:4]1[CH2:5][C:6](=[O:20])[O:7]2)=O.[Li].P(=O)([O-])O[CH2:24][C:25](=[O:36])[C:26](C)(C)[O:27][C:28]1[CH:33]=[CH:32][CH:31]=[CH:30][CH:29]=1>O1CCCC1>[O:36]=[C:25]([CH2:26][O:27][C:28]1[CH:33]=[CH:32][CH:31]=[CH:30][CH:29]=1)/[CH:24]=[CH:1]/[C@H:3]1[C@H:10]([O:11][C:12](=[O:19])[C:13]2[CH:18]=[CH:17][CH:16]=[CH:15][CH:14]=2)[CH2:9][C@H:8]2[C@@H:4]1[CH2:5][C:6](=[O:20])[O:7]2A solution of 548 mg. of (1S,5R,6R,7R)-6-formyl-7-benzoyloxy-2-oxabicyclo[3,3,0]octan-3-one [J. Amer. Chem. Soc. 96: 5865 (1974)] in 20 ml. of absolute tetrahydrofuran is combined with 581 mg. of the lithium salt of dimethyl-2-oxo-3-phenoxypropyl phosphonate, and the mixture is agitated for 1.5 hours at room temperature under argon. The mixture is then combined with 0.3 ml. of glacial acetic acid, concentrated under vacuum, mixed with 100 ml. of methylene chloride, and extracted with 10 ml. of 5% sodium bicarbonate solution and twice with respectively 10 ml. of water. The product is dried with magnesium sulfate, evaporated under vacuum, and the residue of the evaporation is recrystallized from methylene chloride-isopropyl ether, thus obtaining 710 mg. of the title compound as colorless crystals (yield: 87.5% of theory).
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