Br[C:2]1[O:3][C:4]2[C:16]([CH2:17][CH2:18][OH:19])=[CH:15][CH:14]=[CH:13][C:5]=2[C:6]=1[C:7]1[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=1.[CH:20]1([C:26]([OH:28])=O)CC=CCC1.C(O)(=O)C.[N+:33]([O-:38])([N+]([O-])=O)=[O:34]>CCCCCC.C(Cl)(Cl)Cl>[C:26]([O:19][CH2:18][CH2:17][C:16]1[C:4]2[O:3][C:2]([N+:33]([O-:38])=[O:34])=[C:6]([C:7]3[CH:12]=[CH:11][CH:10]=[CH:9][CH:8]=3)[C:5]=2[CH:13]=[CH:14][CH:15]=1)(=[O:28])[CH3:20]The product of step A and 2 g. of 4-cyclohexenecarboxylic acid are dissolved in 25 ml. of acetic acid, and 1.8 g. of dinitrogen tetraoxide in 5 ml. of acetic acid are added dropwise. After stirring 20 minutes at room temperature, the mixture is heated at 45° C. for one hour, then at 55° C. for one hour. The mixture is then partially evaporated to remove residual dinitrogen tetraoxide, poured into water, then extracted with diethyl ether. The ether extracts are washed thrice with water, twice with sodium bicarbonate solution, once with water, and dried. Evaporation provides a residue which is dissolved in hexane-chloroform and fractionated by chromatography on silica gel, using hexane-chloroform as eluent. Thin layer chromatographic analysis determines that two relatively pure components are obtained. Recrystallization of the first main component twice from a hexanebenzene mixture provides yellow flakes of 2-(2-nitro-3-phenyl-7-benzofuranyl)ethyl acetate, m.p. 95°-98° C.
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