C([O:3][C:4](=[O:19])[C@@H:5]1[CH2:9][C@H:8]([C:10]#[N:11])[CH2:7][N:6]1[C:12]([O:14][C:15]([CH3:18])([CH3:17])[CH3:16])=[O:13])C.[OH-].[Na+].C(O)(=O)C.O.[K+].[Br-]>CO>[C:15]([O:14][C:12]([N:6]1[CH2:7][C@@H:8]([C:10]#[N:11])[CH2:9][C@H:5]1[C:4]([OH:19])=[O:3])=[O:13])([CH3:18])([CH3:16])[CH3:17]The cyano ethyl ester (11a) from the previous experiment (2.9 g, 12.1 mmol) was dissolved in 100 mL methanol and 15 mL of 1M NaOH was added over five minutes with good stirring. This was allowed to stir for 16 h at 22° C. and was then treated with 1 mL of 80% acetic acid/water. This solution was then concentrated and worked-up according to method A. The residue crystallized on standing at 5° C., and was recrystallized from EtOAc/hexane to give 2.2 g (76% yield), m.p.=138°-139° C. (decomposition). IR (KBr) 2253 cm-1 (nitrile). 1H NMR δ 1.40/1.46 (2s, 9H), 2.44 (m, 1H), 2.70 (m, 1H), 3.12 (m, 1H), 3.65 (m, 1H), 3.92 (m, 1H), 4.36 (m, 1H). Anal. (C11H16N2O4), C, H, N. The X-ray crystal structure of this compound unambiguously confirmed the expected cis orientation of the nitrile with respect to the carboxylic acid.
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