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Preparation 1 4-[2-(Toluene-4-sulfonyloxymethyl)phenyl]piperidine-1-carboxylic Acid t-Butyl Ester 4-(2-Carboxyphenyl)piperidine-1-carboxylic acid t-butyl ester (5.0 g, 16 mmol, 1.0 eq.) and THF (130 mL, 1.7 mol) were combined at room temperature under nitrogen. Borane dimethyl sulfide complex (2.9 mL, 33 mmol, 2.0 eq.) was added dropwise and the mixture was stirred for 5 minutes, then heated at reflux for 1 hour. The mixture was cooled to room temperature, and the reaction was quenched dropwise with MeOH (40 mL), then concentrated by rotary evaporation. The material was azeotroped with MeOH (2*40 mL). The mixture was then diluted with EtOAc (100 mL), and washed with 1 M HCl (2*50 mL), then NaHCO3 (2*50 mL), then saturated aqueous NaCl (1*50 mL). The organic layer was dried over anhydrous Na2SO4, filtered, and concentrated in vacuo to yield 4-(2-hydroxymethylphenyl)piperidine-1-carboxylic acid t-butyl ester (4.8 g) as a clear, light yellow oil that solidified upon sitting. 1H NMR (CDCl3) delta (ppm) 7.34-7.22 (m, 3H); 7.19 (dt, J=1.6 Hz, 7.2, 1H); 4.73 (s, 2H); 4.32-4.14 (m, 2H); 3.00 (tt, J=4.0 Hz, 12.0, 1H); 2.80 (t, J=11.6 Hz, 2H); 1.78-1.56 (m, 4H); 1.47 (m, 9H). |
4.8 g |
With dimethylsulfide borane complex; In tetrahydrofuran; for 1.08333h;Inert atmosphere; Reflux; |
Example 1 Preparation of 4-(2-Hydroxymethylphenyl)piperidine-1-carboxylic Acid tert-Butyl Ester 4-(2-Carboxyphenyl)piperidine-1-carboxylic acid t-butyl ester (5.0 g, 16 mmol, 1.0 eq.) and THF (130 mL, 1.7 mol) were combined at room temperature under nitrogen. Borane dimethyl sulfide complex (2.9 mL, 33 mmol, 2.0 eq.) was added dropwise and the mixture was stirred for 5 minutes, then heated at reflux for 1 hour. The mixture was cooled to room temperature and the reaction was quenched by adding MeOH (40 mL) dropwise. The mixture was then concentrated by rotary evaporation and the resulting material was azeotroped with MeOH (2*40 mL). The mixture was then diluted with EtOAc (100 mL), and washed with aqueous hydrochloric acid solution (1 M; 2*50 mL), then aqueous saturated sodium bicarbonate solution (2*50 mL), then saturated aqueous sodium chloride solution (1*50 mL). The organic layer was dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo to yield 4-(2-hydroxymethylphenyl)-piperidine-1-carboxylic acid t-butyl ester (4.8 g) as a clear, light yellow oil that solidified upon sitting. 1H NMR (CDCl3) delta (ppm) 7.34-7.22 (m, 3H); 7.19 (dt, J=1.6 Hz, 7.2, 1H); 4.73 (s, 2H); 4.32-4.14 (m, 2H); 3.00 (tt, J=4.0 Hz, 12.0, 1H); 2.80 (t, J=11.6 Hz, 2H); 1.78-1.56 (m, 4H); 1.47 (m, 9H). |
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Example 10 Preparation of 4-(2-Hydroxymethylphenyl)piperidine-1-carboxylic Acid tert-Butyl Ester 4-(2-Carboxyphenyl)piperidine-1-carboxylic acid tert-butyl ester (5.0 g, 160 mmol, 1.0 eq.) and THF (100 mL, 1.0 mol) were combined at room temperature under nitrogen. Borane-THF complex in THF (1.0 M, 32.7 mL, 32.7 mmol, 2.0 eq.) was added dropwise over 10 minutes (5 C. exotherm, gas evolution). The reaction mixture was stirred at room temperature for 5 minutes, then heated at 50 C. for 1 hour. The reaction mixture was cooled to room temperature and the reaction was quenched by slowly adding MeOH (30 mL) (mild exotherm, significant gas evolution). The mixture was then concentrated by rotary evaporation. The resulting material was azeotroped with MeOH (2*50 mL). The crude product was dissolved in EtOAc (100 mL) and washed with saturated aqueous sodium bicarbonate solution (50 mL) and then saturated aqueous sodium chloride solution (50 mL). The organic layer was dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo to yield 4-(2-hydroxymethylphenyl)piperidine-1-carboxylic acid tert-butyl ester (4.4 g) as a clear, light yellow oil that solidified upon sitting. |