Reacción #4592

Ecuación de reacción

sodium cyanamide

DCC

N-hydroxysuccinimide

N-benzoyl-L-leucine

→

N-Benzoyl-L-leucylcyanamide

Rendimiento 42.9%

Disolventes

THF

—

EtOAc petroleum ether THF CH2Cl2 AcOH

water

—

EtOAc petroleum ether AcOH

acetonitrile

Condiciones de reacción

Tratamiento posterior

1. 1
   FiltraciónThe reaction mixture was filtered
2. 2
   Otroto remove the bulk of the DCU
3. 3
   Otrothe filtrate was evaporated in vacuo to dryness
4. 4
   workup.DISSOLUTIONThe resulting semi-solid residue was redissolved in THF
5. 5
   Filtraciónthe mixture filtered
6. 6
   Otroto remove any residual DCU
7. 7
   OtroThe filtrate was evaporated in vacuo
8. 8
   Otroto give crude N-benzoyl-L-leucine N-hydroxysuccinimide ester as a foamy residue
9. 9
   workup.WAITto proceed at room temperature for 24 hours
10. 10
    ConcentraciónThe reaction mixture was then concentrated in vacuo to half its original volume
11. 11
    Filtraciónfiltered
12. 12
    ExtracciónThe filtrate (pH 9) was extracted with ethyl acetate (2×50 ml)
13. 13
    OtroThe aqueous layer was separated
14. 14
    Extracciónextracted with methylene chloride (3×50 ml)
15. 15
    ExtracciónThe methylene chloride extract
16. 16
    Secadowas dried over anhydrous sodium sulfate
17. 17
    Filtraciónfiltered
18. 18
    OtroThe filtrate was evaporated in vacuo
19. 19
    Otroto give 2.80 g (92.4% yield) of crude product as a tacky white solid
20. 20
    OtroThis was triturated with diethyl ether
21. 21
    Otrocollected
22. 22
    Otroto give 1.30 g (42.9% yield of white powdery 11, mp 136°-137° C. [α]D23 +0.7°(c 1.0, CH3OH)
23. 23
    Otroquenching

Procedimiento

DCC (2.41 g, 0.0117 mol) and N-hydroxysuccinimide (1.35 g, 0.0117 mol) were added to a solution of N-benzoyl-L-leucine (2.75 g, 0.0117 mol) in 100 ml of acetonitrile at ice bath temperature. The reaction was allowed to proceed at this temperature for 2 hours. The reaction mixture was filtered to remove the bulk of the DCU and the filtrate was evaporated in vacuo to dryness. The resulting semi-solid residue was redissolved in THF and the mixture filtered to remove any residual DCU. The filtrate was evaporated in vacuo to give crude N-benzoyl-L-leucine N-hydroxysuccinimide ester as a foamy residue. IR (neat, cm-1) 3340 NH), 3060 (C6H5), 1820, 1790, 1740 and 1650 (C=O); NMR (Silanor C, δ from TMS) 7.3-7.9 (m, C6H5), 5.1-5.3 (m, --NH--CH--C=O), 2.8 (s, cycl. --CH2 --CH2 --), 1.6-2.2 (m, CH--CH2 --), 0.9-1.1 (d, (CH3)3CH). This was dissolved in 100 ml of THF and added drop-wise to a solution of sodium cyanamide (1.50 g, 0.0234 mol) in 100 ml of distilled water at ice bath temperature. The reaction was allowed to proceed at room temperature for 24 hours. The reaction mixture was then concentrated in vacuo to half its original volume and filtered. The filtrate (pH 9) was extracted with ethyl acetate (2×50 ml). The aqueous layer was separated, acidified to pH 1.5 with 10% HCl, and extracted with methylene chloride (3×50 ml). The methylene chloride extract was dried over anhydrous sodium sulfate and filtered. The filtrate was evaporated in vacuo to give 2.80 g (92.4% yield) of crude product as a tacky white solid. This was triturated with diethyl ether and collected to give 1.30 g (42.9% yield of white powdery 11, mp 136°-137° C. [α]D23 +0.7°(c 1.0, CH3OH); TLC: Rf =0.93 in EtOAc/petroleum ether/THF/CH2Cl2 / AcOH (50:50:10:50:4) and 0.24 in EtOAc/petroleum ether/AcOH (50:100:1), detected by UV quenching and orange color with ferricyanide spray reagent; IR (Nujol, cm-1) 3300, 3100 (NH), 2230 (C≡N), 1750 and 1630 (C=O); NMR (Silanor-DMSO, δ from TMS) 7.4-8.0 (d, C6H5 --), 4.2-4.6 (m, --NH--CH--C=O), 1.4-1.9 (m, CH--CH2 --), 0.8-1.1 (d, (CH3)2CH--) Anal. Calcd for C14H17N3O2 : C, 64.85; H, 6.61; N, 16.20. Found C, 64.62; H, 6.73; N, 15.93.

Fuente