تفاعل #164476

معادلة التفاعل

(R)-tert-butyl 2-(3,4-dichlorophenyl)-2-hydroxyethyl(2-hydroxyethyl)-carbamate

(2R,3R)-2,3-bis[(4-methylbenzoyl)oxy]butanedioic acid

isopropyl N-isopropoxycarbonyliminocarbamate

HCl

triphenylphosphine

→

(R)-2-(3,4-dichlorophenyl)morpholine (2R,3R)-2,3-bis[(4-methylbenzoyl)oxy]butanedioic acid salt

المردود 22.4%

المذيبات

acetic acid

MTBE

ظروف التفاعل

المعالجة

1. 1
   أخرىIn a 3 neck flask equipped with a mechanical stirrer
2. 2
   workup.ADDITIONthermocouple and addition funnel
3. 3
   workup.ADDITIONDuring the addition
4. 4
   درجة الحرارةthe reaction temperature gradually increased
5. 5
   درجة الحرارةto reflux
6. 6
   درجة الحرارةthe mixture was chilled with an ice bath to 15° C
7. 7
   ترشيحThe resulting precipitate was filtered
8. 8
   غسيلthe filter cake was washed with 2 L of MTBE
9. 9
   تركيزThe filtrate was concentrated to approximately 2 L in vacuo
10. 10
    workup.STIRRINGthe mixture was stirred at 55° C. for 3 h
11. 11
    workup.STIRRINGto stir at RT for 10 h
12. 12
    أخرىquenched with 1 L of 5M NaOH
13. 13
    أخرىThe phases were separated
14. 14
    غسيلthe organic phase was washed with 1 L of brine
15. 15
    تركيزconcentrated in vacuo
16. 16
    أخرىaffording an oil which
17. 17
    أخرىIn a 3 neck flask equipped with a mechanical stirrer
18. 18
    درجة الحرارةthermocouple and heating mantle
19. 19
    workup.ADDITIONwas added crude yellow oil
20. 20
    درجة الحرارةwas heated and to the mixture
21. 21
    أخرىaffording a white slurry
22. 22
    درجة الحرارةThe mixture was heated
23. 23
    درجة الحرارةto reflux
24. 24
    أخرىaffording a clear amber solution
25. 25
    أخرىtransferred to a clean 5 L flask
26. 26
    أخرىa course sparge tube as a filter
27. 27
    درجة الحرارةto cool to −45° C. at ambient temperature
28. 28
    درجة الحرارةcooled with an ice-bath to 12° C
29. 29
    ترشيحThe resulting mixture was filtered over a medium fritted funnel
30. 30
    غسيلwashed with 500 mL of glacial acetic acid
31. 31
    ترشيحfiltered
32. 32
    أخرىdried

الإجراء التجريبي

In a 3 neck flask equipped with a mechanical stirrer, thermocouple and addition funnel using a water bath was added (R)-tert-butyl 2-(3,4-dichlorophenyl)-2-hydroxyethyl(2-hydroxyethyl)-carbamate (588 g, 1.679 mol) followed by MTBE (2.5 L). To the mixture was added triphenylphosphine (528 g, 467 mL, 2.02 mol) followed by isopropyl N-isopropoxycarbonyliminocarbamate (407 g, 390 mL, 2.02 mol) dropwise. During the addition, the reaction temperature gradually increased to reflux. The reaction mixture was allowed to stir at ambient temperature for 1 h. A precipitate occurred and the mixture was chilled with an ice bath to 15° C. The resulting precipitate was filtered, and the filter cake was washed with 2 L of MTBE. The filtrate was concentrated to approximately 2 L in vacuo and returned to the reaction vessel. HCl (1.26 L of 4 M in dioxane, 5.04 mol) was added and the mixture was stirred at 55° C. for 3 h. Effervescence occurred. The mixture was allowed to stir at RT for 10 h and quenched with 1 L of 5M NaOH. The phases were separated and the organic phase was washed with 1 L of brine, and concentrated in vacuo affording an oil which was 98% ee (chiral HPLC). In a 3 neck flask equipped with a mechanical stirrer, thermocouple and heating mantle was added crude yellow oil using glacial acetic acid (2.5 L) The solution was heated and to the mixture was added (2R,3R)-2,3-bis[(4-methylbenzoyl)oxy]butanedioic acid (649 g, 1.68 mol) affording a white slurry. The mixture was heated to reflux affording a clear amber solution. The mixture was vacuum transferred to a clean 5 L flask using a transfer tube and a course sparge tube as a filter. The mixture was seeded and allowed to cool to −45° C. at ambient temperature and then cooled with an ice-bath to 12° C. The resulting mixture was filtered over a medium fritted funnel and washed with 500 mL of glacial acetic acid. The filter cake was slurried with MTBE (500 mL twice), filtered and dried affording (R)-2-(3,4-dichlorophenyl)morpholine (2R,3R)-2,3-bis[(4-methylbenzoyl)oxy]butanedioic acid salt (233 g) as a white solid. The combined mother liquors were concentrated to 2 L in vacuo. The solution was allowed to sit for 12 h, filtered and the filter cake washed with 1 L of MTBE. This afforded an additional 186 g of product for a total of 419 g (40%, >99% ee) of product. To prepare the free base, the salt (178 g, 288 mmol) was added to a 2 L Erlenmeyer flask and diluted with 1 L of MTBE. 2M NaOH (400 mL) was added and the mixture was stirred until clear. The organic phase was separated and the aqueous phase was extracted with 500 mL of MTBE. The combined organic phases were dried over MgSO4 and concentrated in vacuo to afford the free base (R)-2-(3,4-dichlorophenyl)-morpholine (66 g, 100%) as a colorless oil. 1H-NMR (400 MHz, CDCl3) δ 7.50-7.49 (m, 2H), 7.19 (dd, J=1.6, 8.3 Hz, 1H), 4.47 (dd, J=2.4, 10.4 Hz, 1H), 4.09 (s, 1H), 4.08 (dd, J=1.9, 12.9 Hz, 1H), 3.82-3.75 (m, 1H), 3.09 (dd, J=2.5, 12.5 Hz, 1H), 2.97 (dd, J=3.1, 10.2 Hz, 2H), 2.72-2.69 (m, 1H). LC/MS (10%-99% CH3CN (0.035% TFA)/H2O (0.05% TFA)), m/z: M+1 obs=232.3; tR=0.67 min. Chiral HPLC (Astec Chirobiotic V2 column (25 cm×4.6 mm, 5 um), 100% methanol (0.1% NH4TFA, 1.5 mL/min) tR (R)=10.81 min; tR (S)=13.65 min.

المصدر