Structure of 1218998-83-4
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| CAS No. : | 1218998-83-4 |
| Formula : | C10H17NO5 |
| M.W : | 231.25 |
| SMILES Code : | C(C)(C)(C)OC(=O)N1C[C@@H](C[C@@H]1C(=O)O)O |
| English Name : | rel-(2R,4R)-1-(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid |
| MDL No. : | N/A |
* All experimental methods are cited from the reference, please refer to the original source for details. We do not guarantee the accuracy of the content in the reference.

| Yield | Reaction Conditions | Operation in experiment |
|---|---|---|
| 99.1% | With sodium tetrahydroborate In methanol at 0 - 5℃; | 3.b Preparation of product cis-F-1 The reducing agent (4.0 to 5.0 e.q.) was added to the solvent,Cold to a certain temperature,Add the substrate in batches to exotherm,HPLC monitoring reaction,Reaction is completed,The reaction solution was added to water,Cooling to 0 ~ 5C,With dilute hydrochloric acid pH 2 ~ 3, EA extraction(5X * 3). The combined organic phases were washed with saturated brine and dried over anhydrous sodium sulfate. The solvent was evaporated under reduced pressure to give the crude product. The crude productThe product was crystallized from a mixed solvent of ethyl acetate and alkane. |
| 97% | With sodium tetrahydroborate In methanol; water at 4℃; for 15h; | |
| 90% | With sodium tetrahydroborate In methanol at 0℃; for 3.5h; |
| 80% | Stage #1: N-tert-butoxycarbonyl-4-oxo-L-proline With sodium tetrahydroborate In methanol; water at 0 - 4℃; for 0.416667h; Stage #2: With citric acid In water stereoselective reaction; |

| Yield | Reaction Conditions | Operation in experiment |
|---|---|---|
| 97.07% | With sodium hydroxide In water at 25 - 40℃; for 4h; | 1-3 Example 3 Add L-hydroxyproline (100g, 0.76mmol, 1.0eq) and water (200mL) to a 1000mL three-necked flask to dissolve, and stir at 25°C for 30min;Dicarbonyl di-tert-butyl ester (166g, 0.76mmol, 1.0eq) was added dropwise at room temperature, after the dropwise addition, 133.6g of 25wt% sodium hydroxide aqueous solution was added dropwise, and the temperature was controlled at 28°C to pH=8.63;The temperature was raised to 40 °C and stirred for 4 h. After the reaction was completed, the temperature of the system was lowered to 0 °C;3M hydrochloric acid was added dropwise to the three-necked flask to adjust the pH of the system to 2.12, a large amount of white solids were precipitated, continued stirring for 30 min, suction filtration, the filter cake was rinsed twice with 50 g of water, and pumped to no droplets to obtain a wet product;The wet product was placed in a blast drying oven at 45° C. for blast drying for 6 hours to obtain 171.2 g of a white crystalline solid with a yield of 97.07% and a HPLC purity of 99.924%. |
| 95% | With sodium hydroxide In tetrahydrofuran; water | 2 Commercially available (Aldrich) compound 6 (525 mg, 4 mmol) was dissolved in water (10 mL) and THF (5 L). NaOH (aq) was added to give pH 9-10. Boc anhydride (959 mg, 4.4 mmol) was dissolved in THF (2 mL) and added to the reaction dropwise. The reaction was maintained at a pH 9-10 with NaOH (aq). Upon completion, the reaction was acidified to pH of 3 with dilute HC1 (aq) and extracted with EtOAc (2x). The organic extracts were dried over anhydrous sodium sulfate and concentrated under reduced pressure to give a Boc-protected proline (compound 6a) as a solid. This solid was washed with hexanes (3x) and dried under high vacuum to give the intermediate (882 mg, 95%) which was then dissolved in anhydrous DMF (5 mL).HOBt (641 mg, 4.18 mmol) and EDAC (874 mg, 4.56 mmol) were added and stirred for 15 minutes. Compound 2 (1.87 g, 4.2 mmol) and TEA (1.1 ml, 7.6 mmol) were added and the reaction was stirred for 4 hours. The reaction material was diluted with EtOAc and washed with saturated aqueous sodium bicarbonate solution (3x) and saturated aqueous sodium chloride solution. The organic extracts were dried over anhydrous sodium sulfate and concentrated under reduced pressure. The material was purified with CombiFlash (0-10% MeOH in DCM) to give compound 7 (345mg, 15%). Mass Spectrum (m/e): (M+H)+ 623.1, (M-H)- 620.6. |
| 84.7% | Stage #1: hydroxy L-proline With dmap In dichloromethane for 0.25h; Large scale; Stage #2: di-<i>tert</i>-butyl dicarbonate In dichloromethane at 20 - 30℃; Large scale; | 1; 2 Example 2 Take 8500 g of methylene chloride, 1310 g of 4-hydroxy-L-proline, and 122 g of DMAP, add them to a 20L reaction flask, and stir for 15 minutes. Take 2400 g of BOC anhydride and slowly add it dropwise to the reaction solution, maintaining the internal temperature below 30°C. After dripping, keep the internal temperature at 20-30 and stir overnight. TLC, the raw material has reacted completely, and processed. 5000g of water was added to the reaction solution and stirred at 20-30°C for 1 hour. Liquid separation, the organic phase was dried over anhydrous sodium sulfate, and concentrated under reduced pressure. 1955 g of white solid was obtained, with a yield of 84.7% and a purity of 98.5%. |
| 77% | With sodium hydroxide In tetrahydrofuran; water at 20℃; | 127A (2S,4S)-1-(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid To a solution of (2S,4S)-4-hydroxypyrrolidine-2-carboxylic acid (3.9 g, 29.7 mmol) in THF (26.7 mL) and water(13.3 mL) was added di-tert-butyl dicarbonate (7.14 g, 32.7 mmol) and sodium hydroxide (2.0 N, 22.9 mL, 45.8 mmol)and the mixture stirred at room temperature overnight. The mixture then had 10% citric acid (50 mL) added followed byEtOAc and extraction with water and brine. The organic extract was dried, filtered and concentrated to afford 5.31 g(77%) of the title compound. MS (ESI) m/z 232 (M+H)+. |
| With triethylamine In water; acetone | ||
| With triethylamine In methanol for 0.75h; Heating; Yield given; | ||
| With sodium hydroxide In water; N,N-dimethyl-formamide at 20℃; | 1.1 Di-tert-butyl dicarbonate (0.532 mL, 2.291 mmol) was added to a solution of cis- 4-hydroxy-L-ρroline (265 mg, 2.02 mmol) in DMF (5 mL) and aqueous sodium hydroxide (2 mL, 2 mmol). The reaction mixture was stirred at room temperature overnight. Allyl bromide (0.18 mL, 2.08 mmol) was added and the resulting mixture was stirred at room temperature overnight. The reaction mixture was diluted with ethyl acetate and washed with dilute aqueous HCl, water, saurated sodium bicarbonate and brine, dried over magnesium sulfate, filtered and concentrated under vacuum to afford the title compound as a clear oil. | |
| 5.31 g (77%) | With sodium hydroxide; citric acid In tetrahydrofuran; water; ethyl acetate | 127.A (2S,4S)-1-(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid Example 127A (2S,4S)-1-(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid To a solution of (2S,4S)-4-hydroxypyrrolidine-2-carboxylic acid (3.9 g, 29.7 mmol) in THF (26.7 mL) and water (13.3 mL) was added di-tert-butyl dicarbonate (7.14 g, 32.7 mmol) and sodium hydroxide (2.0 N, 22.9 mL, 45.8 mmol) and the mixture stirred at room temperature overnight. The mixture then had 10% citric acid (50 mL) added followed by EtOAc and extraction with water and brine. The organic extract was dried, filtered and concentrated to afford 5.31 g (77%) of the title compound. MS (ESI) m/z 232 (M+H)+. |
| With triethylamine In methanol at 20℃; for 23.5h; Reflux; | (2S,4R)-1-(Tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic Acid (Boc-trans-L-4-hydroxyproline, v) General procedure: To a stirred solution of trans-L-4-hydroxyproline i (2.0 g,15.3 mmol) in MeOH (36.0 mL) was added Et3N (4.0 mL,28.7 mmol) and Boc anhydride (6.7 g, 30.5 mmol) and the reaction was refluxed for 3.5 h, cooled to room temperature, and stirred for 20 h. Solvent was removed under vacuum and the residue cooled to 0oC. Following the addition of NaH2PO4 (150 mg), the solution was acidified to pH 2 with 0.5 M HCl.The mixture was stirred at 0oC for 30 min before extractingthe product with EtOAc (420 mL). The combined organic layers were dried with MgSO4 and filtered. The solvent was removed under vacuum yielding v as a white foam (3.23 g,14 mmol, 92 %) | |
| Stage #1: di-<i>tert</i>-butyl dicarbonate; hydroxy L-proline In tetrahydrofuran Stage #2: With water; sodium hydrogencarbonate In tetrahydrofuran | ||
| With sodium hydrogencarbonate In water; acetone at 20℃; | 1 The L-hydroxyproline obtained in Step S5 was mixed with sodium hydrogencarbonate and dissolved in water. Acetone was added, followed by the dropwise addition of di-tert-butyl dicarbonate then reacted at room temperature overnight, followed by post-treatment to give tert-butoxycarbonyl-N-hydroxy Proline | |
| 0.13 g | With triethylamine In methanol at 0 - 20℃; for 16h; | |
| With sodium hydroxide In tetrahydrofuran at 0 - 20℃; for 6h; | 1.4; 2.4; 10.4 4) Preparation of Boc-L-hydroxyproline: L-Hydroxyproline (9.0 g, 68.7 mmol) was dissolved in tetrahydrofuran (82.5 mL) and sodium hydroxide solution (1 M, 82.5 mL) at 0 °C. Di-tert-butyl dicarbonate (15.75 mL, 68.7 mmol) was added to an ice-water bath. The mixture was reacted at room temperature for 6 h until complete reaction was detected by thin layer chromatography. The reaction solution was concentrated to about 80 mL in vacuo, cooled in an ice-water bath, acidified to pH 2-3 with 1M hydrochloric acid, and diluted with 100 mL of ethyl acetate. Extract with ethyl acetate (50 mL×3). The combined organic layers were washed twice with 50 mL of brine, and then dried over anhydrous sodium sulfate to obtain a colorless oil, which could be used continuously without purification. | |
| 91.24 % | With N-ethyl-N,N-diisopropylamine In dichloromethane at 25℃; |

| Yield | Reaction Conditions | Operation in experiment |
|---|---|---|
| 95% | Stage #1: N-tert-butoxycarbonyl-L-cis-4-hydroxyproline With caesium carbonate In N,N-dimethyl-formamide at 0℃; Stage #2: benzyl bromide In N,N-dimethyl-formamide | |
| 95% | Stage #1: N-tert-butoxycarbonyl-L-cis-4-hydroxyproline With caesium carbonate In methanol; water at 0 - 25℃; for 0.75h; Inert atmosphere; Stage #2: benzyl bromide In acetonitrile at 18 - 25℃; for 20h; Inert atmosphere; | |
| 2.21 g | With triethylamine In N,N-dimethyl-formamide at 0 - 20℃; |
| 2.98 g | With caesium carbonate In N,N-dimethyl-formamide at 65℃; for 3h; | A mixture of (2S,4S)-1-(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid (5.22 g, 22.57 mmol), cesium carbonate (16.18 g, 49.7 mmol) and benzyl bromide (3.22 mL, 27.1 mmol) in DMF (70 mL) was heated in an oil bath at 65° C. for 3 h. The mixture was then poured into iced water (500 ml) and extracted with EtOAc (100 mL, ×2). The organic layer was washed with water, 0.2 M NaOH, and brine, dried over MgSO4, filtered and evaporated in vacuo. The residual oil was purified by FCC (20% to 60% Acetone-Hexane) to yield Cap W-29/Cap W-30 Step A (2.98 g) as a colorless viscous oil.1H NMR (400 MHz, CDCl3) δ 7.54-7.31 (m, 5H), 5.42-5.27 (m, 1H), 5.27-5.11 (m, 2H), 4.40-4.26 (m, 1H), 3.80-3.51 (m, 2H), 2.36 (dtd, J=14.4, 9.8, 4.6 Hz, 1H), 2.22-2.03 (m, 1H), 1.57-1.41 (m, 5H), 1.37 (s, 5H). |
| 2.98 g | With caesium carbonate In N,N-dimethyl-formamide at 65℃; for 3h; | A A mixture of (2S,4S)- 1 -(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2- carboxylic acid (5.22 g, 22.57 mmol), cesium carbonate (16.18 g, 49.7 mmol) and benzyl bromide (3.22 mL, 27.1 mmol) in DMF (70 mL) was heated in an oil bath at 65 °C for 3 h. The mixture was then poured into iced water (500 ml) and extracted with EtOAc (100 mL, X2). The organic layer was washed with water, 0.2 M NaOH, and brine, dried over MgS04, filtered and evaporated in vacuo. The residual oil was purified by FCC (20% to 60% Acetone-Hexane) to yield Cap W-29/Cap W-30 Step A (2.98 g) as a colorless viscous oil. NMR (400MHz, CDC13) δ 7.54 - 7.31 (m, 5H), 5.42 - 5.27 (m, 1H), 5.27 - 5.11 (m, 2H), 4.40 - 4.26 (m, 1H), 3.80 - 3.51 (m, 2H), 2.36 (dtd, J=14.4, 9.8, 4.6 Hz, 1H), 2.22 - 2.03 (m, 1H), 1.57 - 1.41 (m, 5H), 1.37 (s, 5H). |
| With sodium carbonate In N,N-dimethyl-formamide | ||
| With caesium carbonate In N,N-dimethyl-formamide at 50℃; for 4h; | To a solution of 18-12 (10 g, 43.24 mmol, 1 eq) and cesium carbonate (14.09 g, 43.24 mmol, 1 eq) in dimethylformamide (100 mL) was added benzyl bromide (8.14 g, 47.57 mmol, 5.65 mL, 1.1 eq) drop-wise. The resulting mixture was stirred at 50°C for 4 hours. LCMS showed part of the starting material remained and the mixture was stirred for another 5 hours at 50°C. TLC petroleum ether: ethyl acetate =1:1) showed the starting material was consumed. The reaction mixture was filtered. The aqueous phase was poured in to water (500 mL), extracted with ethyl acetate (200 mLx3). The combined organic phase was washed with brine (500 mLx2), dried over anhydrous sodium sulfate, filtered and concentrated in vacuo The residue was purified by column (SiO2, petroleum ether: ethyl acetate =10:1 to 1:1) to afford 18-13 (13 g, 36.88 mmol, 85.28% yield, 91.17% purity) as colorless gum. LCMS: RT = 0.79 min, m/z 222.2 [M-Boc+H]+, purity: 91.17%. SFC: RT = 0.567 min, de% = 89.1%. 1H NMR (CDCl3, 400MHz): d 7.38 - 7.35 (m, 5H), 5.31 - 5.12 (m, 2H), 4.35 - 4.31 (m, 2H), 3.69 - 3.55 (m, 2H), 2.37 - 2.29 (m, 1H), 2.08 - 2.03 (m, 1H), 1.47 & 1.35 (s, 9H). | |
| 5.90g | With trimethylamine In tetrahydrofuran at 20℃; for 24h; Inert atmosphere; Cooling with ice; | 2 Synthesis of Compound 7 A flamed dried 1000 mL rb flask under N2 (g) was charged with a magnetic stir bar, cis-N-Boc-hydroxyproline, compound 6 (5.00 g, 21.6 mmol) and dry THF (430 mL). The flask was placed on an ice bath and to this stirring solution was added benzylbromide (3.35 mL, 28.1 mmol) and trimethylamine (3.91 mL, 28.1 mmol) dropwise. The reaction was allowed to warm up to room temperature and stirred for 24 hr. At this time, solvent was removed by rotary evaporation and the residue was dissolved in DCM (400 mL), washed with 10% HCl (200 mL), water (200 mL), sat. NaHCO3 (200 mL) and brine (200 mL). The organic layer was then dried (MgSO4, anhydrous), filtered and concentrated by rotary evaporation. The residue was dissolved in minimal DCM and purified by flash chromatography (silica gel, 5% MeOH/DCM) to yield Compound 7 as a colorless oil (5. 90 g, 18.3 mmol). Rf=0.65 in 10% MeOH/DCM. 1H NMR (CDCl3, 400 MHz): δ 7.35 (m, 5 H), 5.36 (m, 1 H), 5.32 (m, 1 H), 5.56 (m, 2H), 3.15 (br, 1 H), 2.30 (m, 1 H), 2.07 (dt, J=16 Hz, 4 Hz, 1 H), 1.39 (s, 9 H). |

| Yield | Reaction Conditions | Operation in experiment |
|---|---|---|
| 100% | Stage #1: tert-butyldimethylsilyl chloride; N-tert-butoxycarbonyl-L-cis-4-hydroxyproline With 1H-imidazole In dichloromethane; N,N-dimethyl-formamide at 20℃; for 2h; Stage #2: With methanol; lithium hydroxide; water at 20℃; for 2h; Stage #3: With hydrogenchloride In methanol; water | 142 Example 142: (4S)-1-(re/t-butoxycarbonyl)-4-hydroxy-L-proline tert-butyl dimethyl silyl ether; (4S)-1-(Terf-butoxycarbonyl)-4-hydroxy-L-proline (14.4 g, 62 mmol, 1.0 equiv) and imidazole (21.1 g, 310 mmol, 5 equiv) were dissolved in dichloromethane (100 mL) and N, N- dimethylformamide (DMF) (20 mL). Terf-butyl chlorodimethyl silane (20.6 g, 137 mmol, 2.2 equiv) was added and the reaction mixture was stirred for 2 h at room temperature. The reaction mixture was poured into water (600 mL), the dichloromethane layer was withdrawn, concentrated in vacuo and then taken up in 20% ether/hexanes. The organic layer was washed with brine and concentrated in vacuo. The crude product was dissolved in methanol (80 mL) and a solution of lithium hydroxide monohydrate (4.4 g, 105 mmol, 1.7 equiv) in water (100 mL) was added. The homogeneous mixture was stirred at ambient temperature for 2h. The reaction mixture was poured into water (600 mL) and acidified to pH 3.0 using 1 N hydrochloric acid (HCI). The aqueous layer was extracted three times with 10% ether/hexanes. The organic layer was washed with brine and concentrated in vacuo for 18 h which gave the title compound of Example 142 as a solid. (22.0 g, 100% yield): LCMS (ESI+) for C16H31NO5Si m/z 346 (M + H)+. |
| 100% | With 1H-imidazole In N,N-dimethyl-formamide Inert atmosphere; | |
| 96% | With 1H-imidazole In dichloromethane at 20℃; for 12h; Inert atmosphere; | Intermediate 2: (2S,4S)-1 -(tert-Butoxycarbonyl)-4-((tert-butyldimethylsilyl)oxy)- pyrrolidine-2-carboxylic acid A mixture of (2S,4S)-1-tert-butoxycarbonyl-4-hydroxy-pyrrolidine-2-carboxylic acid (CAS Number 87691-27-8; 5 g, 21.6 mmol), tert-butylchlorodimethylsilane (3.91 g, 25.9 mmol), imidazole (2.21 g, 32.4 mmol) in DCM (3 ml_) was degassed and purged 3 times with N2 and then the mixture was stirred at rt for 12 h under N2 atmosphere. The reaction mixture was quenched by addition of aq. NH4CI (60 ml_), diluted with water (100 ml_) and extracted with DCM (200 ml_ x 3). The combined organic layers were washed with brine (100 ml_ x 3), dried over anhydrous sodium sulfate, filtered and evaporated to afford (2S,4S)-1-tert- butoxycarbonyl-4-[tert-butyl(dimethyl)silyl]oxy-pyrrolidine-2-carboxylic acid (7.2 g, 20.8 mmol, 96% yield) as an off-white oil.1H NMR (400 MHz, DMSO-d6) d ppm 4.42 - 4.20 (m, 1 H), 4.26 - 4.07 (m, 1 H), 3.64 - 3.44(m, 1 H), 3.14 - 2.99 (m, 1H), 2.43 - 2.31 (m, 1H), 1.91 - 1.76 (m, 1 H), 1.40 - 1.33 (m, 9H),0.85 - 0.76 (m, 9H), 0.23 - 0.16 (m, 6H). |
| 80% | Stage #1: tert-butyldimethylsilyl chloride; N-tert-butoxycarbonyl-L-cis-4-hydroxyproline With 1H-imidazole In N,N-dimethyl-formamide at 0 - 20℃; for 24h; Inert atmosphere; Stage #2: With lithium hydroxide monohydrate In tetrahydrofuran; methanol at 0 - 20℃; for 2h; Inert atmosphere; | 1.i [00153] Scheme 1 & 2: Synthesis of Serine, cis and trans-hydroxyproline derivatives [00154] Scheme 1 step (i): (2S,4S)-(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid (500 mg, 2.16 mmol) and imidazole (744 mg, 10.80 mmol) were weighed into an oven-dried round bottomed flask (RBF) and dissolved in dry DMF (6 mL). The reaction mixture was cooled to 00C and TBSCl in dry DMF (652 mg, 4.32 mmol) was added dropwise under N2 gas. The reaction mixture was then left to warm up to room temperature and stirred for 24 hours. After removal of excess DMF using N2 gas at 500C, the residue was suspended in ethyl acetate and washed twice with water, thrice with chilled 1 M HCl and once with brine. The organic layer was dried over anhydrous Na2SO4 and filtered. The filtrate was concentrated under reduced pressure to a colorless oil. The oil was dissolved in methanol (3 mL) and THF (4 mL) and the solution cooled to 00C. LiOH.H2O (227 mg, 5.40 mmol) in water (3 mL) was added dropwise and the mixture was allowed to warm to room temperature and stirred for 2 hours. The pH of the solution was adjusted to 2-3 using chilled 1 M HCl and the product 2 (i) was collected as a pure, white precipitate after suction filtration. |
| 79% | With 1H-imidazole In N,N-dimethyl-formamide at 20℃; for 16h; | |
| 67% | With 1H-imidazole In N,N-dimethyl-formamide at 20℃; for 2h; | 9.1; 10.1 Step 1: (2S,4S)-1-(tert-butoxycarbonyl)-4-[(tert-butyldimethylsilyl)oxy]pyrrolidine-2-carboxylic acid To a stirred solution of (2S,4S)-1-(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid(5.00 g, 21.6 mmol, 1.00 equiv.) and imidazole (3.39 g, 49.7 mmol, 2.30 equiv.) in DMF (50mL) was added TBDMSCI (4.89 g, 32.4 mmol, 1.50 equiv.) in portions at room temperature.The resulting mixture was stirred at room temperature for 2 h. The resulting mixture was dilutedwith EtOAc (150 mL), washed with water (50 mL) and dried over anhydrous Na2SO4. Afterfiltration, the filtrate was concentrated under reduced pressure. The residue was purified byreverse-phase chromatography (column, C18 silica gel; mobile phase, MeCN in water (10mmol/L NH4HCO3), 10% to 50% gradient in 10 min; detector, UV 254 nm) to give (2S,4S)-1-(tert-butoxycarbonyl)-4-[(tert-butyldimethylsilyl)oxy]pyrrolidine-2-carboxylic acid (5.0 g, 67%yield) as a colourless oil. |
| 30% | With 1H-imidazole In dichloromethane; N,N-dimethyl-formamide at 0 - 25℃; for 2h; | Synthesis of (2S,4S)-1-(tert-butoxycarbonyl)-4-((tert-butyldimethylsilyl) oxy)pyrrolidine-2-carboxylic acid: tert-butyldimethylsilyl chloride (7.17 g, 47.6 mmol) was added dropwise to a solution of (2S,4S)-1-(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2- carboxylic acid (5 g, 21.6 mmol) and imidazole (7.36 g, 108 mmol) in a mixture of dichloromethane (50.0 mL) and dimethylformamide (10.0 mL) at 0 °C. The reaction mixture was then stirred at 25 °C for 2 h. After concentration, the reaction mixture was purified by preparative HPLC(Column: Waters Xbridge 150*25mm 10µm, water-CAN, B%, 0 - 60, 8 min.) to give (2S,4S)-1-(tert-butoxycarbonyl)-4-((tert-butyldimethylsilyl)oxy)pyrrolidine-2-carboxylic acid (2.20 g, 6.37 mmol, 30% yield) as a colorless oil.1H NMR: (400 MHz, DMSO-d6) δ = 4.36 (dd, J = 4.8, 9.6 Hz, 1H), 4.21-3.97 (m, 2H), 3.57-3.40 (m, 1H), 3.17-3.01 (m, 1H), 2.42-2.19 (m, 1H), 1.88-1.71 (m, 1H), 1.39 (s, 3H), 1.34 (s, 6H), 0.83 (d, J = 4.0 Hz, 9H), 0.06-0.13 (m, 6H). |
| With 1H-imidazole In dichloromethane; N,N-dimethyl-formamide at 20℃; for 18h; | Intermediate 8; (25,45)- 1 -(?er?-butoxycarbonyl)-4-(ieri-butyldimethylsilyloxy)pyrrolidine-2-carboxylic acid (21S',41S)-l-(ieri-Butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid (5.31 g, 22.96 mmol) and imidazole (7.82 g, 115 mmol) were combined in dichloromethane (106 mL) and dimethylformamide (22 mL) at ambient temperature and treated with portionwise addition of tert- butylchlorodimethylsilane (7.61 g, 50.5 mmol). The mixture was stirred for 18 hours then diluted with water and extracted into ethyl acetate and concentrated to provide the title compound. | |
| 10.9 g | With 1H-imidazole In N,N-dimethyl-formamide at 20℃; for 19h; | 34 3-((2S,4S)-4-{4-[1-(5-Cyanopyridin-2-yl)-3-methyl-1H-pyrazol-5-yl]piperazin-1-yl}pyrrolizin-2-ylcarbonyl)thiazolidine trihydrochloride (8q) 4.1.34 3-[(2S,4S)-1-(tert-Butoxycarbonyl)-4-hydroxypyrrolidinylcarbonyl]thiazolidine (24) To a solution of N-(tert-Butoxycarbonyl)-cis-4-hydroxy-l-proline (23) (5.00 g, 21.6 mmol) and imidazole (6.48 g, 95.2 mmol) in DMF (60 mL) was added tert-butyldimethylsilyl chloride (7.16 g, 47.5 mmol) at room temperature. After stirring at room temperature for 19 h, to the mixture were added water (60 mL) and a 10% citric acid aqueous solution (200 mL) under ice-cooling. The mixture was extracted with ethyl acetate. The extract was washed with brine, dried and concentrated under reduced pressure to give (2S,4S)-1-(tert-butoxycarbonyl)-4-(tert-butyldimethylsilyloxy)pyrrolidine -2-carboxylic acid (10.9 g) as a light tan solid. |
| 1.49 g | With 1H-imidazole In dichloromethane; N,N-dimethyl-formamide at 20℃; for 6h; | G1.a a) (25,45)-I -(tert-Butoxycarbonyl)-4-((tert-butyldimethylsilyl)oxy)pyrrolidine-2-carboxylic acid a) (25,45)-I -(tert-Butoxycarbonyl)-4-((tert-butyldimethylsilyl)oxy)pyrrolidine-2-carboxylic acidA solution of (2S,4S)-1 -(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid (CASregistry 87691-27-8) (592 mg, 2.56 mmol) and imidazole (CAS registry 288-32-4) (871 mg,12.80 mmol) were combined in DCM I DMF (1 2/2.4 ml) and treated with TBDMSCI (CASregistry 18162-48-6) (849 mg, 5.63 mmol) at it The resulting mixture was stirred at rt for 6 h, diluted with EtOAc, washed with sat. aqu. NH4CI soln, dried over MgSO4 and concentrated under reduced pressure to afford a colorless oil (1.49 g, crude).HPLC RtM1 =1.20 mm; ESIMS: 346 [(M+H)].1H NMR (400 MHz, DMSO-d6): 12.12 (brs, 1H), 4.45-4.31 (m, 1H), 4.28-4.05 (m, 1H), 3.65-3.44 (m, 1H), 3.13-2.99 (m, 1H), 2.43-2.24 (m, 1H), 1.75-1.84 (m, 1H), 1.38-1.33 (m, 9H),0.89-0.81 (m, 9H), 0.02 (m, 6H). |
| Stage #1: tert-butyldimethylsilyl chloride; N-tert-butoxycarbonyl-L-cis-4-hydroxyproline With 1H-imidazole In dichloromethane; N,N-dimethyl-formamide at 20℃; Stage #2: With hydrogenchloride; lithium hydroxide monohydrate In methanol; water for 2h; | 127B (2S,4S)-1-(tert-butoxycarbonyl)-4-(tert-butyldimethylsilyloxy)pyrrolidine-2-carboxylic acid To a solution of Example 127A (5.31 g, 22.96 mmol) and imidazole (7.82 g, 115 mmol) in dichloromethane(106 mL) and DMF (21.3 mL) was added tert-butyldimethylsilyl chloride (7.61 g, 50.5 mmol) and the mixture stirred atroom temperature overnight. The mixture then had water (425 mL) added and the solution was extracted with EtOAcand the organic extract concentrated to a residue that was dissolved in 25% EtOAc and 75% hexanes then extractedwith brine and the organic extract concentrated to a solid. The resultant solid was dissolved in methanol (65 mL) andwater (85 mL) then lithium hydroxide monohydrate (1.93 g, 46 mmol) added and the solution stirred at room temperaturefor 2 h. Afterwards water (106 mL) and a solution of 1N aqueous hydrochloric acid was added until a pH of 2 was reached.The mixture was then extracted with a mixture of 25% EtOAc and 75% hexanes, the organic extract dried, filtered andconcentrated to give the title compound as a colorless solid. MS (ESI) m/z 346 (M+H)+. | |
| With 1H-imidazole In dichloromethane at 20℃; for 12h; Inert atmosphere; | 3.a; 6.a Step a. A mixture of (2S,4S)-1-(te/f-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid (5.00 g, 21.6 mmol), te/f-butylchlorodimethylsilane (3.91 g, 25.9 mmol), imidazole (2.21 g, 32.4 mmol) in DCM (30 ml_) was degassed and purged with N2 3 times, and then the mixture was stirred at rt for 12 h under N2 atmosphere. Upon completion, the reaction mixture was quenched by addition of aq. NH4CI solution (60 ml_) and water (100 ml_), and then extracted with DCM (200 ml_ x 3). The combined organic layers were washed with brine (100 ml_ x 3), dried over Na2SC>4 and evaporated to give (2S,4S)-1-(te/f-butoxycarbonyl)-4-((tert- butyldimethylsilyl)oxy)pyrrolidine-2-carboxylic acid (7.2 g, crude) as a colorless oil.1H NMR (400 MHz, DMSO-d6) d ppm 4.42 - 4.20 (m, 1 H), 4.26 - 4.07 (m, 1 H), 3.64 - 3.44 (m, 1 H), 3.14 - 2.99 (m, 1H), 2.43 - 2.31 (m, 1H), 1.91 - 1.76 (m, 1 H), 1.40 - 1.33 (m, 9H), 0.85 - 0.76 (m, 9H), 0.23 - 0.16 (m, 6H). | |
| With 1H-imidazole In N,N-dimethyl-formamide at 20℃; Inert atmosphere; | (2S,4S)-1-(tert-butoxycarbonyl)-4-((tert-butyldimethylsilyl)oxy)pyrrolidine-2-carboxylic acid To a mixture of (2S,4S)-1-(tert-butoxycarbonyl)-4-hydroxypyrrolidine-2-carboxylic acid (1 g, 4.33 mmol) in DMF (10 mL) was added TBSCl (650 mg, 4.33 mmol) and imidazole (589 mg, 8.66 mmol). The mixture was stirred at room temperature for 16 hours. After the reaction was completed, the resulting solution was diluted with water (50 mL) and extracted with EtOAc (20 mL x 3). The combined organic phases were washed with brine, dried over Na2SO4, concentrated under vacuum to give crude (2S,4S)-1-(tert-butoxycarbonyl)-4-((tert-butyldimethylsilyl)oxy) pyrrolidine-2-carboxylic acid (0.9 g) as a yellow oil which was used directly in next step. |

| Yield | Reaction Conditions | Operation in experiment |
|---|---|---|
| 95% | With N-ethyl-N,N-diisopropylamine; HATU In dichloromethane at 0 - 20℃; Inert atmosphere; | 1 1,1-dimethylethyl(2S,4S)-2-[({(1R,2S)-2-ethenyl-1-[(ethyloxy)carbonyl]cyclopropyl}amino)carbonyl]-4-hydroxy-1-pyrrolidinecarboxylate To a solution of (4S)-1-[(1,1-dimethylethyl)oxy]carbonyl}-4-hydroxy-L-proline (1.80 g, 7.8 mmol), ethyl (1R,2S)-1-amino-2-ethenylcyclopropanecarboxylate hydrochloride (1.49 g, 7.8 mmol) and HATU (3.26 g, 8.6 mmol) in dichloromethane (80 mL) which had been cooled to 0° C. was added diisopropylethylamine (2.9 mL, 16.4 mmol) and the solution was stirred at 0° C. for 30 min and them room temperature for 5 h under a nitrogen atmosphere. The reaction was concentrated in vacuo and purified by silica gel chromatography eluting with 70-100% hexanes/ethyl acetate. The eluent was concentrated to about 200 mL and washed with 10% aqueous potassium carbonate solution (50 mL) and the organic layer dried (MgSO4) and concentrated in vacuo to afford intermediate 1 as a white foam (2.72 g, 95% yield).1H NMR (400 MHz, DMSO-d6) δ ppm 1.08-1.19 (m, 3H) 1.24 (dd, J=9.33, 5.12 Hz, 1H) 1.28-1.45 (m, 9H) 1.54-1.67 (m, 1H) 1.67-1.81 (m, 1H) 2.05-2.20 (m, 1H) 2.20-2.41 (m, 1H) 3.05-3.22 (m, 1H) 3.41-3.57 (m, 1H) 3.91-4.09 (m, 3H) 4.07-4.23 (m, 1H) 4.98-5.19 (m, 2H) 5.19-5.32 (m, 1H) 5.40-5.82 (m, 1H) 8.55-8.87 (m, 1H). LC-MS (APCI): m/z 369.19 (M+H)+. |
| 95% | With N-ethyl-N,N-diisopropylamine; HATU In dichloromethane at 0 - 20℃; for 5.5h; Inert atmosphere; | |
| 55% | With N-ethyl-N,N-diisopropylamine; HATU In dichloromethane at 0 - 20℃; | 1B Carboxylic acid 1b (4.08 mmol) was diluted with 50 mL of DCM, cooled to 0° C., then consecutively treated with DIEA (4.12 g, 32.64 mmol), cyclopropyl-derived amino-acid hydrochloride salt 1c (0.78 g, 4.08 mmol), and HATU (1.94 g, 5.10 mmol). The reaction mixture was warmed to room temperature and closely monitored using mass spectrometric analysis. Once the reaction was complete, it was transferred to a 250 mL separatory funnel with 75 mL EtOAc, at which time it was extracted with saturated aqueous NaHCO3 (2×20 ml) and brine (2×20 ml). The organic phase was dried over anhydrous Na2SO4, filtered, and then concentrated in vacuo. The residue was purified by silica gel flash chromatography using gradient elution with hexanes:EtOAc (5:1→3:1→1:1→1:2→1:5) yielding the dipeptide 1d (0.826 g, 55%). |
| 55% | With N-ethyl-N,N-diisopropylamine; HATU In dichloromethane at 0 - 20℃; | 1; IB; B Carboxylic acid Ib (4.08 mmol) was diluted with 50 mL of DCM, cooled to 0 0C, then consecutively treated with DIEA (4.12 g, 32.64mmol), cyclopropyl-derived amino-acid hydrochloride salt Ic (0.78 g, 4.08 mmol), and HATU (1.94 g, 5.10 mmol). The reaction mixture was warmed to room temperature and closely monitored using mass spectrometric analysis. Once the reaction was complete, it was transferred to a 250 mL separatory funnel with 75 mL EtOAc, at which time it was extracted with saturated aqueous NaHCO3 (2 x 20 ml) and brine (2 x 20 ml). The organic phase was dried over anhydrous Na2SO4, filtered, and then concentrated in vacuo. The residue was purified by silica gel flash chromatography using gradient elution with hexanes:EtOAc (5: 1- »3: 1- »1: 1- »1:2- »1 :5) yielding the dipeptide Id (0.826 g, 55 %). MS (ESI) m/z = 369.3 (M+H)+. |
| 55% | With N-ethyl-N,N-diisopropylamine; HATU In dichloromethane at 0 - 20℃; | 1.1B Carboxylic acid 1-b (4.08 mmol) was diluted with 50 mL of DCM, cooled to 0° C., then consecutively treated with DIEA (4.1 g, 32.6 mmol), cyclopropyl-derived amino-acid hydrochloride salt 1-c (0.78 g, 4.1 mmol), and HATU (1.9 g, 5.10 mmol). The reaction mixture was allowed to warm to room temperature and closely monitored using mass spectrometric analysis. Once the reaction was complete, it was transferred to a 250 mL separatory funnel with 75 mL EtOAc, at which time it was extracted with saturated aqueous NaHCO3 (2×20 ml) and brine (2×20 ml). The organic phase was dried over anhydrous Na2SO4, filtered, and then concentrated in vacuo. The residue was purified by silica gel flash chromatography using gradient elution with hexanes:EtOAc (5:1→3:1→1:1→1:2→1:5) yielding the dipeptide 1-d (0.826 g, 55%).MS (ESI) m/z=369.3 (M+H)+. |
| 55% | With N-ethyl-N,N-diisopropylamine; HATU In dichloromethane at 20℃; | 1.1B Step 1B. Carboxylic acid 1b (4.08 mmol) was diluted with 50 mL of DCM, cooled to 0° C., then consecutively treated with DIEA (4.1 g, 32.6 mmol), cyclopropyl-derived amino-acid hydrochloride salt 1c (0.78 g, 4.1 mmol), and HATU (1.9 g, 5.10 mmol). The reaction mixture was allowed to warm to room temperature and closely monitored using mass spectrometric analysis. Once the reaction was complete, it was transferred to a 250 mL separatory funnel with 75 mL EtOAc, at which time it was extracted with saturated aqueous NaHCO3 (2×20 ml) and brine (2×20 ml). The organic phase was dried over anhydrous Na2SO4, filtered, and then concentrated in vacuo. The residue was purified by silica gel flash chromatography using gradient elution with hexanes:EtOAc (5:1→3:1→1:1→1:2→1:5) yielding the dipeptide 1d (0.826 g, 55%).MS (ESI) m/z=369.3 (M+H)+. |
| 55% | With N-ethyl-N,N-diisopropylamine; HATU In dichloromethane at 0 - 20℃; | 1B Step 1B. Carboxylic acid 1b (4.08 mmol) was diluted with 50 mL of DCM, cooled to 0° C., then consecutively treated with DIEA (4.12 g, 32.64 mmol), cyclopropyl-derived amino-acid hydrochloride salt 1c (0.78 g, 4.08 mmol), and HATU (1.94 g, 5.10 mmol). The reaction mixture was warmed to room temperature and closely monitored using mass spectrometric analysis. Once the reaction was complete, it was transferred to a 250 mL separatory funnel with 75 mL EtOAc, at which time it was extracted with saturated aqueous NaHCO3 (2×20 ml) and brine (2×20 ml). The organic phase was dried over anhydrous Na2SO4, filtered, and then concentrated in vacuo. The residue was purified by silica gel flash chromatography using gradient elution with hexanes:EtOAc (5:1→3:1→1:1→1:2→1:5) yielding the dipeptide 1d (0.826 g, 55%). MS (ESI) m/z=369.3 (M+H)+. |
| With N-ethyl-N,N-diisopropylamine; HATU In N,N-dimethyl-formamide at 0℃; for 1h; | 1.A 1A. To a solution of commercially available Cis-Boc-hydroxyproline 1-1 (12.72 g, 55 mol) and amino acid ester 1-2 (10.54 g, 55 mol) in 65 ml DMF was added HATU (20.9 g, 55 mmol) and DIEA (28.7 ml, 165 mmol). The coupling was carried out at 0° C. over a period of 1 hour. The reaction mixture was diluted with 500 mL EtOAc, and directly washed with 1M NaHCO3 (4×100 ml) and brine (2×50 ml). The organic phase was dried over anhydrous Na2SO4, filtered, and then concentrated in vacuo, affording the dipeptide 1-3 that was identified by HPLC (Retention time=8.9 min, 30-70%, 90% B). MS (ESI) m/z=369.18 (M+H)+. | |
| With N-ethyl-N,N-diisopropylamine; HATU In N,N-dimethyl-formamide at 0℃; for 1h; | 1.1A IA. To a solution of commercially available C-Boc-hydroxyproline I--I(12.72g, 55 mol) and amino acid ester l_-2 (10.54g, 55 mol) in 65 ml DMF was added HATU (20.9g, 55 mmol) and DIEA (28.7 ml, 165 mmol). The coupling was carried out at 0 0C over a period of 1 hour. The reaction mixture was diluted with 500 mL EtOAc, and directly washed with IM NaHCO3 (4x 100 ml) and brine (2x 50 ml). The organic phase was dried over anhydrousNa2SO4, filtered, and then concentrated in vacuo, affording the dipeptide 1-3 that was identified by HPLC (Retention time = 8.9 min, 30-70%, 90%B). MS (ESI): m/z = 369.18 [M+H]. |

| Yield | Reaction Conditions | Operation in experiment |
|---|---|---|
| 94% | With O-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium tetrafluoroborate; N-ethyl-N,N-diisopropylamine In DMF (N,N-dimethyl-formamide) at 18 - 22℃; for 3.5h; | 4 EXAMPLE 4; Preparation of Dipeptides; Synthesis of dipeptide 1 A mixture of BOC-HYDROXYPROLINE P2 (50.0 g, 216 MMOL), vinyl-ACCA methyl ester P1 (42.25 g, 238 mmol, 1.1 EQUIV.), TBTU (76.36 g, 238 MMOL, 1.1 equiv. ) and DIPEA (113 mL, 649 mmol, 3 equiv. ) in DMF (800 mL) was stirred at R. T. under a nitrogen atmosphere. After 3.5 h, the solvent was evaporated and the residue extracted with EtOAc. The extract was washed with hydrochloric acid (10%), saturated sodium bicarbonate and brine. The organic phase was then dried over magnesium sulfate, filtered and evaporated to afford an oil. After drying overnight under high vacuum, dipeptide 1 was obtained as a yellow foam (72. 0 g, 94%, purity >95% by HPLC). |
| 94% | With O-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium tetrafluoroborate; N-ethyl-N,N-diisopropylamine In N,N-dimethyl-formamide at 20℃; for 3.5h; Inert atmosphere; | 1 A mixture of Boc-hydroxyprohne P2 (50 0 g, 216 mmoi), vinyl-ACCA methyl ester P1 (23) (42 25 g, 238 mmoi), TBTU (76 36 g, 238 mmoi) and DiPEA (113 rrsL, 649 mmoi) in DMF (800 iτsL) is stirred at RT under a nitrogen atmosphere After about 3.5 h the solvent is evaporated and the residue is extracted with EtOAc. The extract is washed with HCI (10%) saturated sodium bicarbonate and brine. The organic phase is then dried over MgSO4, filtered and evaporated to afford an oil After drying overnight under high vacuum, dipeptide 36 is obtained (72 0 g, 94% yield, punty >95% by HPLC) |