Reaction #1375810

Reaction equation

hydrochloric acid

tyrosine-tert-butyl ester

benzaldehyde

sodium bicarbonate

sodium cyanoborohydride

→

N-Benzyl-tyrosine-tert-butyl ester

Solvents

methanol

Conditions

Workup

1. 1
   Otherafter substantial evaporation of methanol, it
2. 2
   workup.STIRRINGis shaken out with ethyl acetate
3. 3
   DryingThe organic phase is dried on anhydrous magnesium sulfate
4. 4
   Filtrationfiltered
5. 5
   Concentrationconcentrated by evaporation
6. 6
   OtherThe residue is chromatographed on silica gel with diethyl ether/hexane/triethylamine
7. 7
   Concentrationconcentrated by evaporation

Procedure

16.9 g (71.5 mmol) of tyrosine-tert-butyl ester and 8.33 g (78.6 mmol) of benzaldehyde are stirred in 50 ml of methanol for 3 hours at 24° C. and then mixed with 3.37 g (53.6 mmol) of sodium cyanoborohydride. After 24 hours of stirring at room temperature, the batch is adjusted to pH 2 by careful addition of semiconcentrated hydrochloric acid, then neutralized with concentrated aqueous sodium bicarbonate solution and, after substantial evaporation of methanol, it is shaken out with ethyl acetate. The organic phase is dried on anhydrous magnesium sulfate, filtered and concentrated by evaporation. The residue is chromatographed on silica gel with diethyl ether/hexane/triethylamine; the product-containing fractions are combined and concentrated by evaporation.

Source