Reacción #54609

Ecuación de reacción

Boc-Ser(Bzl)-Ser(Bzl)-Glu(OBzl)-OH

HCl

Boc-Thr(Bzl)-OSu

Et3N

Et3N

→

Boc-Thr(Bzl)-Ser(Bzl)-Ser(Bzl)-Glu(OBzl)-OH

Disolventes

DMSO

THF

DMF

Condiciones de reacción

Tratamiento posterior

1. 1
   OtroThe mixture was evaporated to dryness
2. 2
   Otrothe residue evaporated twice more with THF
3. 3
   Otroto give a solid mass (59.3 g; mp 161°-165°)
4. 4
   OtroIt was collected
5. 5
   Lavadowashed with ether
6. 6
   Temperaturato maintain
7. 7
   Otrothe reaction slightly basic
8. 8
   OtroSome insoluble matter formed
9. 9
   Filtraciónwas filtered off
10. 10
    Otrothe filtrate evaporated to an oil which
11. 11
    workup.DISSOLUTIONwas dissolved in EtOAc (1.5 liters)
12. 12
    Lavadowashed with 5% HOAc, H2O (2 times)
13. 13
    Secadodried (Na2SO4)
14. 14
    Otroevaporated to a solid mass
15. 15
    OtroThe product was recrystallized from EtOAc and petroleum ether
16. 16
    Otroto yield

Procedimiento

Boc-Ser(Bzl)-Ser(Bzl)-Glu(OBzl)-OH (71.6 g, 104 mmol) was treated with 2.7 liters of freshly prepared 3.9 N HCl in THF for 45 minutes. The mixture was evaporated to dryness and the residue evaporated twice more with THF to give a solid mass (59.3 g; mp 161°-165°). It was collected and washed with ether and stirred in 500 ml of DMF with Boc-Thr(Bzl)-OSu (38.2 g, 94 mmol) in the presence of Et3N (25 ml) at 0° for 1 hour and then at 25° for 15 hours. More Et3N (14.5 ml) was added in serveral portions during this time to maintain the reaction slightly basic. Some insoluble matter formed was filtered off and the filtrate evaporated to an oil which was dissolved in EtOAc (1.5 liters), washed with 5% HOAc, H2O (2 times), dried (Na2SO4), and evaporated to a solid mass. The product was recrystallized from EtOAc and petroleum ether to yield, 64.8 g (78.1%); mp 115°-118°; [α]D25 =+11.64° (c 1, DMSO).

Fuente