反応 #159071

反応方程式

4-methylene-pyrrolidine-1,2-dicarboxylic acid 1-benzyl ester 2-methyl ester

diethyl zinc

diiodomethane

diethyl zinc

trifluoroacetic acid

4-methylene-pyrrolidine-1,2-dicarboxylic acid 1-benzyl ester 2-methyl ester

N-methylmorpholine-N-oxide

trifluoroacetic acid

→

5-aza-spiro[2.4]heptane-5,6-dicarboxylic acid 5-benzyl ester 6-methyl ester

収率 65.1%

溶媒

dichloromethane

dichloromethane

THF water acetone

dichloromethane

反応条件

後処理

1. 1
   その他An oven-dried 3-neck round bottom flask was equipped with a nitrogen inlet
2. 2
   workup.ADDITIONadaptor and a 250 mL addition funnel
3. 3
   その他The third neck was sealed with a septum
4. 4
   workup.ADDITIONThe flask was charged with a stir bar
5. 5
   workup.WAITAfter another 20 minutes
6. 6
   洗浄was then rinsed with another 10 mL dichloromethane
7. 7
   温度to warm to RT
8. 8
   workup.STIRRINGstirred for 110 hours (about 5 days) after which the reagents
9. 9
   その他were quenched with saturated aqueous ammonium chloride (˜150 mL)
10. 10
    workup.ADDITIONThe contents of the flask were slowly poured into a 2 L sep funnel
11. 11
    workup.ADDITIONcontaining saturated aqueous sodium bicarbonate (˜800 mL)
12. 12
    抽出The aqueous phase was extracted three times with 300 mL ethyl acetate
13. 13
    乾燥The combined organics were dried over magnesium sulfate
14. 14
    濃縮concentrated
15. 15
    その他to provide the crude material
16. 16
    workup.STIRRINGAfter stirring at RT for 7 h
17. 17
    その他the reagents were quenched with 1 M aqueous sodium thiosulfate (˜100 mL)
18. 18
    workup.ADDITIONThe contents of the flask were then poured into a 1 L sep funnel
19. 19
    workup.ADDITIONcontaining water (˜300 mL)
20. 20
    抽出The aqueous phase was extracted three times with 300 mL dichloromethane
21. 21
    乾燥The combined organics were dried over magnesium sulfate
22. 22
    濃縮concentrated
23. 23
    その他The crude residue was purified by silica column chromatography (5% to 45% EtOAc/hexane)

実験手順

An oven-dried 3-neck round bottom flask was equipped with a nitrogen inlet adaptor and a 250 mL addition funnel. The third neck was sealed with a septum. The flask was charged with a stir bar, dichloromethane (120 mL) and diethyl zinc (1.0 M in hexane, 118 mL, 118 mmol) then cooled to 0° C. in an ice bath. The addition funnel was charged with dichloromethane (40 mL) and trifluoroacetic acid (9.1 mL, 118 mmol). After the diethyl zinc solution had cooled to 0° C. (about 25 minutes), the trifluoroacetic acid solution was added dropwise over 20 minutes to the stirred reaction mixture. After stirring for another 20 minutes at 0° C., diiodomethane (9.5 mL, 118 mmol) was added slowly over 4 minutes. After another 20 minutes, 4-methylene-pyrrolidine-1,2-dicarboxylic acid 1-benzyl ester 2-methyl ester (8.10 g, 29.4 mmol) was added in 30 mL dichloromethane by cannula. The flask containing 4-methylene-pyrrolidine-1,2-dicarboxylic acid 1-benzyl ester 2-methyl ester was then rinsed with another 10 mL dichloromethane and this solution was also transferred to the reaction mixture by cannula. The reaction mixture was allowed to warm to RT and stirred for 110 hours (about 5 days) after which the reagents were quenched with saturated aqueous ammonium chloride (˜150 mL). The contents of the flask were slowly poured into a 2 L sep funnel containing saturated aqueous sodium bicarbonate (˜800 mL). The aqueous phase was extracted three times with 300 mL ethyl acetate. The combined organics were dried over magnesium sulfate and concentrated to provide the crude material. The crude material was dissolved in 3:1:1 THF/water/acetone (165 mL) then treated with N-methylmorpholine-N-oxide (3.45 g, 29.4 mmol) and osmium tetroxide (4 wt % in water, 5 mL, 0.818 mmol). After stirring at RT for 7 h, the reagents were quenched with 1 M aqueous sodium thiosulfate (˜100 mL). The contents of the flask were then poured into a 1 L sep funnel containing water (˜300 mL). The aqueous phase was extracted three times with 300 mL dichloromethane. The combined organics were dried over magnesium sulfate and concentrated. The crude residue was purified by silica column chromatography (5% to 45% EtOAc/hexane) to provide 5-aza-spiro[2.4]heptane-5,6-dicarboxylic acid 5-benzyl ester 6-methyl ester as a clear oil (5.54 g, 19.15 mmol, 65%) as a clear oil. 1H NMR (CDCl3) δ 7.36-7.29 (m, 5H), 5.21-5.04 (m, 2H), 4.56-4.47 (m, 1H), 3.75 (s, 1.5H), 3.60 (m, 1.5H), 03.51-3.37 (m, 2H), 2.32-2.25 (m, 1H), 1.87-1.80 (m, 1H), 0.64-0.51 (m, 4H).

出典