[OH:1][C:2]([CH3:18])([CH3:17])[C@H:3]([NH:10][C:11](=[O:16])C(Cl)(Cl)Cl)[C:4]1[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1.C(=O)([O-])[O-].[K+].[K+]>C(O)C>[C:4]1([C@@H:3]2[C:2]([CH3:18])([CH3:17])[O:1][C:11](=[O:16])[NH:10]2)[CH:9]=[CH:8][CH:7]=[CH:6][CH:5]=1To a solution of (14) (1.655 g, 5.33 mmol) in ethanol (140 ml) was added potassium carbonate (0.369 g. 2.67 mmol) and the solution was refluxed for 30 minutes. After concentration in vacuo, dichloromethane was added and the mixture was washed with saturated aqueous sodium chloride solution. Concentration in vacuo gave crude crystalline solid which was purified by recrystallisation in ethyl acetate/pentane to give the title compound (15) (0.939 g, 92%); mp 149° C.; νmax (CHCl3) 1753 cm-1 ; [α]D25 (c 0.5 in CHCl3)=-77.6; (Found: C, 69.32; H, 7.05; N, 7.38. C11H13NO2 requires C, 69.09; H, 6.85; N, 7.33%); δH (200 MHz; CDCl3) 0.93 (3H, s, C(CH3)2), 1.61 (3H, s, C(CH3)2), 4.66 (1H, s, CHPh), 6.25 (1H, s, NH), 7.25-7.44 (5H, m, ArCH); δC (125 MHz; CDCl3 23.53 (CH3), 28.04 (CH3), 65.93 (CH), 84.63 (C), 126.67 (ArCH), 128.72 (ArCH), 128.93 (ArCH), 137.16 (C), 159.75 (CO) ; m/z (CI+, NH3) 192 (M+ +1).
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