[O:1]1[C:5]2[CH:6]=[CH:7][C:8]([CH:10]([C:12]3[CH:20]=[CH:19][C:15]4[O:16][CH2:17][O:18][C:14]=4[CH:13]=3)O)=[CH:9][C:4]=2[O:3][CH2:2]1.C1(C)C=CC(S(O)(=O)=O)=CC=1.[CH3:32][CH2:33][O:34][C:35]([CH2:37][N+:38]([O-:40])=[O:39])=[O:36]>>[O:1]1[C:5]2[CH:6]=[CH:7][C:8]([CH:10]([C:12]3[CH:20]=[CH:19][C:15]4[O:16][CH2:17][O:18][C:14]=4[CH:13]=3)[CH:37]([N+:38]([O-:40])=[O:39])[C:35]([O:34][CH2:33][CH3:32])=[O:36])=[CH:9][C:4]=2[O:3][CH2:2]1The alcohol of Example 17 is dissolved in 5 mL of nitro ethyl acetate. A catalytic amount of p-toluene-sulfonic acid is added and the reaction mixture is heated to 120° C. for 3 hours. Excess nitro ethyl acetate is removed by distillation and the residue is purified by silica gel chromatography eluting with 15% ethyl acetate-hexane to give 2.25 g (79%) of product as a yellow oil;
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