Reaktion #1772029

Reaktionsgleichung

acetaldehyde

(S)-4-amino-2-(tert-butoxycarbonylamino)butanoic acid

water MeOH

NaCNBH3

acetaldehyde

→

(S)-2-amino-4-(diethylamino)butanoic acid

Reaktionsbedingungen

Aufarbeitung

1. 1
   Sonstigethe cooling bath was removed
2. 2
   workup.STIRRINGthe reaction was stirred for 20.5 hr
3. 3
   SonstigeMost of the MeOH component was removed in vacuo
4. 4
   workup.ADDITIONthe remaining mixture was treated with concentrated HCl until its pH
5. 5
   SonstigeThe volatile component was removed in vacuo
6. 6
   workup.ADDITIONthe residue was treated with 4 M HCl/dioxane (20 mL)
7. 7
   workup.STIRRINGstirred at ambient condition for 7.5 hr
8. 8
   SonstigeThe volatile component was removed in vacuo
9. 9
   Sonstigethe residue was purified with Dowex® 50WX8-100 ion-exchange resin (column
10. 10
    Waschenwas washed with water
11. 11
    Waschenthe compound was eluted with dilute NH4OH
12. 12
    Sonstigeprepared from 18 ml of NH4OH and 282 ml of water)

Vorschrift

NaCNBH3 (1.60 g, 24.2 mmol) was added in batches to a chilled (˜15° C.) water/MeOH (12 mL each) solution of (S)-4-amino-2-(tert-butoxycarbonylamino)butanoic acid (2.17 g, 9.94 mmol). A few minutes later acetaldehyde (2.7 mL, 48.1 mmol) was added drop-wise over 2 min, the cooling bath was removed, and the reaction mixture was stirred at ambient condition for 3.5 hr. An additional acetaldehyde (2.7 mL, 48.1 mmol) was added and the reaction was stirred for 20.5 hr. Most of the MeOH component was removed in vacuo, and the remaining mixture was treated with concentrated HCl until its pH reached ˜1.0 and then heated for 2 hr at 40° C. The volatile component was removed in vacuo, and the residue was treated with 4 M HCl/dioxane (20 mL) and stirred at ambient condition for 7.5 hr. The volatile component was removed in vacuo and the residue was purified with Dowex® 50WX8-100 ion-exchange resin (column was washed with water and the compound was eluted with dilute NH4OH, prepared from 18 ml of NH4OH and 282 ml of water) to afford intermediate (S)-2-amino-4-(diethylamino)butanoic acid as an off-white solid (1.73 g).

Quelle