[NH2:1][C:2]1[C:7]2[CH2:8][CH2:9][O:10][C:6]=2[C:5]([C:11]2[O:15][N:14]=[C:13]([CH:16]3[CH2:21][CH2:20][N:19](C(OCC)=O)[CH2:18][CH2:17]3)[N:12]=2)=[CH:4][C:3]=1[Cl:27].[OH-].[K+]>CC(O)C>[Cl:27][C:3]1[C:2]([NH2:1])=[C:7]2[CH2:8][CH2:9][O:10][C:6]2=[C:5]([C:11]2[O:15][N:14]=[C:13]([CH:16]3[CH2:21][CH2:20][NH:19][CH2:18][CH2:17]3)[N:12]=2)[CH:4]=1A mixture of intermediate 3 (10 g) and potassium hydroxide (14 g) in 2-propanol (200 ml) was stirred and refluxed for 6 hours. The reaction mixture was cooled and the solvent evaporated. Water was added to the residue and evaporated again. The residue was stirred in water and the resulting precipitate was filtered off, washed with water and purified by column chromatography on silica gel (eluent: CH2Cl2 /(CH3 OH/NH3) 90/10). The pure fractions were collected and the solvent evaporated, yielding 5.14 g (64%) of 5-chloro-2,3-dihydro-7-[3-(4-piperidinyl)-1,2,4-oxadiazol-5-yl]-4-benzofuranamine (intermediate 4; mp. 219.0° C.).
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