[Synthesis]
Method B: Synthesis of (S)-piperidine-1,2-dicarboxylic acid 1-benzyl ester
1. To a stirred mixed solution of (S)-piperidine-1,2-dicarboxylic acid 1-benzyl ester 2-methyl ester (8.0 g, 28.8 mmol) in MeOH (75 mL) and water (38 mL) at 0 °C was slowly added powdered KOH (1.78 g, 31.7 mmol).
2. The reaction mixture was stirred at room temperature for 16 hours.
3. Upon completion of the reaction, MeOH was removed under vacuum.
4. The residue was diluted with water and washed with DCM.
5. The aqueous layer was acidified with 1.0 M HCl to pH < 7 and subsequently extracted three times with ethyl acetate.
6. The organic extracts were combined, dried with anhydrous Na2SO4, filtered and concentrated in vacuum to afford (L)-N-CBZ-piperidinecarboxylic acid as a light yellow oil (7.6 g, 100% yield).
Product Characterization:
1H NMR (400 MHz, CD3OD) δ 1.36-1.61 (2H, m), 1.70-1.85 (3H, m), 2.28-2.40 (1H, m), 3.05-3.26 (1H, m), 4.06-4.14 (1H, m), 4.89-5.26 (4H, m), 7.37-7.48 (5H, m );
13C NMR (100 MHz, CD3OD) δ 20.5,20.6 (CH2), 24.6,24.7 (CH2), 26.6 (CH2), 41.8,41.9 (CH2), 54.5,54.7 (CH), 67.2,67.3 (CH2), 127.6 (CH), 127.9 (CH), 128.4 (CH), 136.9 (C), 173.4 (CO).
Note: Method C does not provide detailed information. |