合成路线1

1) The Friedel-Crafts condensation of 4,7-dichloro-2,3-dihydrobenzofuran-2-carboxylic acid ethyl ester (I) with benzoyl chloride (II) by means of AlCl3 in dichloroethane, followed by hydrolysis with ethanolic NaOH gives 5-benzoyl-4,7-dichloro-2,3-dihydrobenzofuran-2-carboxylic acid (III), which by reaction with hydroxylamine in refluxing pyridine is converted into the corresponding oxime (IV). Finally, this compound is cyclized with NaH in DMF or with KOH in ethanol. 2) The Friedel-Crafts condensation of (V) with (II) as before gives 2-hydroxy-4-methoxybenzophenone (XVI), which by cyclocondensation with hydroxylamine as before is converted into 6-methoxy-3-phenyl-1,2-benzisoxazole (XVII). Demethylation of (XVII) as already indicated yields 6-hydroxy-3-phenyl-1,2-benzisoxazole (XVIII), which is converted into the allyloxy derivative (XIX). The rearrangement of (XIX) with N,N-dimethylamine as before affords the 7-allyl derivative (XX), which is cyclized with m-chloroperbenzoic acid (m-CPBA) to 3-phenyl-7,8-dihydrofuro[2,3-g]-1,2-benzisoxazole-7-methanol (XXI). Finally, this compound is chlorinated with SO2Cl2 in CH2Cl2 yielding compound (XV), which is oxidized with CrO3 / H2SO4 or KMnO4 in dichloromethane.