[Cl:1][C:2]1[CH:16]=[CH:15][C:5]([C:6]([C@@H:8]2[CH2:11][CH2:10][C@H:9]2[C:12]([OH:14])=O)=O)=[CH:4][CH:3]=1.[NH:17]([CH2:19][CH:20]([OH:23])[CH2:21][CH3:22])[NH2:18].C1(C)C=CC=CC=1>O>[Cl:1][C:2]1[CH:3]=[CH:4][C:5]([C:6]2[CH:8]3[CH:9]([C:12](=[O:14])[N:17]([CH2:19][CH:20]([OH:23])[CH2:21][CH3:22])[N:18]=2)[CH2:10][CH2:11]3)=[CH:15][CH:16]=1Into a flask equipped with a stirrer, heating mantle and Dean - Stark water separator is charged 7.2 g (0.30mole) of a mixture of cis-and trans-2-p-chlorobenzoylcyclobutane carboxylic acid, 3.5g(0.033 mole) of 1-hydrazino-2-butanol and 100 ml. of toluene. The mixture is stirred and refluxed until the water layer in the Dean-Stark tube remains constant (ca. 5 hr). The solvent is removed in vacuo on a rotary evaporator, and the residue is dissolved in hot diethyl ether and allowed to cool to room temperature. The resultant solid is filtered off and yields 2-(p-chlorophenyl)-4-(2-hydroxybutyl) 3,4-diazabicyclo [4.2.0]-oct-2-ene-5-one(Isomer B;m.p. 133°-135°). The filtrate is further concentrated to give Isomer A (m.p. 115.5°-119° C.).
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