C(O[C:4](=[O:15])[CH2:5][CH2:6][CH2:7][CH2:8][C:9]1[CH:14]=[CH:13][CH:12]=[CH:11][CH:10]=1)C.CC[O-].[Na+].[Na].C(OCC)(=O)[C:22]([O:24]CC)=[O:23].S(=O)(=O)(O)O>C1(C)C=CC=CC=1.C(O)C>[O:15]=[C:4]([CH2:5][CH2:6][CH2:7][CH2:8][C:9]1[CH:10]=[CH:11][CH:12]=[CH:13][CH:14]=1)[C:22]([OH:24])=[O:23]47.9 g of 5-phenylvaleric acid ethyl ester are added to a sodium ethylate suspension, prepared from 6.4 g of sodium and 100 ml of ethanol with subsequent evaporation of excess ethanol and addition of 100 ml of toluene. 44.1 g of diethyl oxalate are added dropwise, whilst stirring, and the mixture is heated under reflux for 2.5 hours. After cooling, the solution is stirred with 500 ml of ice-water and the mixture is acidified to pH 2 with 2 N sulphuric acid. Extraction several times with methylene chloride gives, after drying, filtration through a short silica gel column and concentration, 62.1 g of 3-ethoxycarbonyl-2-oxo-6-phenylhexanoic acid ethyl ester, which is reacted according to (a), without further purification.
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