Cl[C:2]1[CH2:6][CH2:5][CH2:4][C:3]=1[CH:7]=O.[CH2:9]([O:11][C:12](=[O:22])[CH2:13][NH:14][CH2:15][C:16]1[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=1)[CH3:10]>C1(C)C=CC=CC=1>[CH2:15]([N:14]1[C:13]([C:12]([O:11][CH2:9][CH3:10])=[O:22])=[CH:7][C:3]2[CH2:4][CH2:5][CH2:6][C:2]1=2)[C:16]1[CH:21]=[CH:20][CH:19]=[CH:18][CH:17]=146.7 g (0.358 mol) of 2-chloro-1-formylcyclopent-1-ene are dissolved in 400 ml of toluene. 138 g (0.716 mol) of N-benzylglycine ethyl ester are added. The mixture is refluxed for one hour, the ester of reaction being separated off via a water separator. After cooling, any precipitate formed is filtered off with suction and the toluene solution is washed with water, dried and concentrated. The residue is taken up in 300 ml of ethanol, 600 ml of 2N hydrochloric acid are added and the mixture is extracted 3x with petroleum ether. The petroleum ether phase is washed with 2×175 ml of ethanol/2N hydrochloric acid 1:2 and then with 100 ml of saturated NaHCO3 solution, the organic phase is dried over MgSO4, stirred with active charcoal and filtered with suction, and the filtrate is evaporated in vacuo.
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