C([O:9][CH2:10][C:11]1([CH2:14][C:15]#N)[CH2:13][CH2:12]1)(=O)C1C=CC=CC=1.[OH-:17].[K+].[N+](=C)=[N-].CC[O:24][CH2:25]C>C(O)C.CCCCCC>[OH:9][CH2:10][C:11]1([CH2:14][C:15]([O:24][CH3:25])=[O:17])[CH2:12][CH2:13]1
The nitrile of Step 3 (0.388 mol) was dissolved in ethanol (400 mL), 8N KOH (800 mL) was added and the reaction mixture was heated to reflux overnight. Most of the ethanol was evaporated and ice was added to the mixture. Concentrated HCl was added (600 mL) dropwise at 0° C. (without warming over 10° C. inside the solution) until obtention of pH approx. 1. The acid was then extracted with EtOAc two times and the organic phases were washed 2 times with brine and dried over Na2SO4. The solvent was evaporated and the solid was dissolved in THF (500 mL). A solution of diazomethane in Et2O (about 1.7 L, 0.85 mol) was added at 0° C. until the yellow color remained and no more acid could be seen by TLC. The solvent was evaporated and the residual oil was purified by flash chromatography using 1:1 to 2:1 EtOAc:hexane to yield 28.2 g, (50% yield) of the title compound. 1H NMR (CDCl3) δ0.55 (4H, m), 2.45 (2H, s), 2.55 (1H, t), 3.5 (2H, d), 3.70 (3H, s).
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