Reaktion #1004081

Reaktionsgleichung

L-tyrosine methyl ester hydrochloride

di-t-butylcarbonate

triethylamine

→

N-Boc-L-tyrosine methyl ester

Ausbeute 95.5%

Lösungsmittel

toluene

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.WAITAfter further keeping at 20° C. for 4 hrs
2. 2
   Waschenthe reaction mass was washed with 5% hydrochloric acid (328.1 g) and 5% aqueous sodium bicarbonate (378.1 g)
3. 3
   SonstigeThe toluene solution thus obtained
4. 4
   Trocknenwas dried over suitable amount of magnesium sulfate
5. 5
   Einengenconcentrated to about a half of the volume under reduced pressure
6. 6
   workup.ADDITIONTo the concentrate was added dropwise n-hexane (329.5 g) at room temperature over 1 hr
7. 7
   workup.WAITAfter keeping at 0° C. overnight
8. 8
   Sonstigeprecipitates
9. 9
   Filtrationwere filtered
10. 10
    Sonstigedried under reduced pressure

Vorschrift

L-tyrosine methyl ester hydrochloride 2 (104.3 g, 0.45 mol) and di-t-butylcarbonate (DBC, 98.2 g, 0.45 mol) were suspended in toluene (521.3 g), and triethylamine (50.1 g, 0.495 mol) was added dropwise thereto at 20° C. over 1.5 hrs. After further keeping at 20° C. for 4 hrs, the reaction mass was washed with 5% hydrochloric acid (328.1 g) and 5% aqueous sodium bicarbonate (378.1 g). The toluene solution thus obtained was dried over suitable amount of magnesium sulfate and then concentrated to about a half of the volume under reduced pressure. To the concentrate was added dropwise n-hexane (329.5 g) at room temperature over 1 hr. After keeping at 0° C. overnight, precipitates were filtered and dried under reduced pressure to give N-Boc-L-tyrosine methyl ester 3 (126.9 g, yield 95.5%) as white crystals.

Quelle