反应详情

To a stirred solution of sodium methoxide in methanol, 11 ml (1 eq., 24.8% w/w solution) was added 5 g of (S)-isoserine. The mixture was stirred at room temperature for 15 minutes until a homogeneous solution was obtained. Ethyltrifluoroacetate, 7 ml (1.25 q.) was added. The mixture was stirred for 30 minutes after the addition. The completeness of the reaction was monitored by 1H-NMR. The mixture was concentrated under reduced pressure to as low a volume as possible. To the residue 50 ml ethylacetate was added. The mixture was cooled to 0°-5° C., 25 ml of 2N HCl (1 eq.) was added, followed by 5 g of solid sodium chloride. The organic layer was separated. The aqueous layer was reextracted with 50 ml of ethylacetate. The combined organic extracts were dried (over 5 g of anhydrous magnesium sulfate), filtered and concentrated under reduced pressure to 20 ml. To it 50 ml heptane was added with stirring in an ice-bath for 30 minutes. The product was filtered and dried to yield 8.86 g (93%) of N-trifluoroacetyl-(S)-isoserine; m.p. 142°-143° C.; [a]D20 : +12.4 (1%, H2O); 1H-NMR (D2O) w 3.78 (d, 2H, J=5.48 Hz), 4.53 (t, 1H, J=5.48 Hz).

1. customwas obtained
2. stirringThe mixture was stirred for 30 minutes
3. additionafter the addition
4. concentrationThe mixture was concentrated under reduced pressure to as low a volume as possible
5. additionTo the residue 50 ml ethylacetate was added
6. temperatureThe mixture was cooled to 0°-5° C.
7. customThe organic layer was separated
8. dry with materialThe combined organic extracts were dried (over 5 g of anhydrous magnesium sulfate)
9. filtrationfiltered
10. concentrationconcentrated under reduced pressure to 20 ml
11. additionTo it 50 ml heptane was added
12. stirringwith stirring in an ice-bath for 30 minutes
13. filtrationThe product was filtered
14. customdried