Reaktion #641202

Reaktionsgleichung

zinc

DL-α-lipoic acid

ethyl chloroformate

isopropylamine

→

aimed compound

N-(6,8-dimercaptooctanoyl)isopropylamine zinc

Lösungsmittel

acetonitrile

acetonitrile

triethylamine

Reaktionsbedingungen

Aufarbeitung

1. 1
   workup.ADDITIONwas quickly added
2. 2
   workup.STIRRINGstirring
3. 3
   SonstigeThe solvent was evaporated under reduced pressure, and water
4. 4
   workup.ADDITIONwas added to the residue
5. 5
   Temperaturthe mixture then was cooled down
6. 6
   SonstigePrecipitated pale yellow crystals
7. 7
   Filtrationwere collected by filtration
8. 8
   workup.DISSOLUTIONdissolved in 60 ml of tetrahydrofuran (THF)
9. 9
   workup.ADDITIONTo this were added
10. 10
    Sonstige20 ml of 50% acetic acid aqueous solution and 2.0 g of zinc powder and reaction
11. 11
    workup.WAITwas allowed for two hours at 50° C.
12. 12
    workup.STIRRINGwith stirring
13. 13
    Sonstigewas separated out by filtration
14. 14
    Einengenthe filtrate was concentrated
15. 15
    workup.ADDITIONAfter addition of water to the residue
16. 16
    Sonstigeprecipitated white crystals
17. 17
    Filtrationwere collected by filtration
18. 18
    SonstigeRecrystallized from THF/acetic acid/water

Vorschrift

4.2 g of DL-α-lipoic acid and 2.4 g of triethylamine were dissolved in 50 ml of acetonitrile and cooled down to −65° C. with stirring. To this was gradually added 2.4 g of ethyl chloroformate dropwise. Twenty minutes after the completion of the dropwise addition, 1.5 g of isopropylamine dissolved in 30 ml of acetonitrile was quickly added, and stirring was continued for 30 minutes and, further one hour at room temperature. The solvent was evaporated under reduced pressure, and water was added to the residue and the mixture then was cooled down. Precipitated pale yellow crystals were collected by filtration, dissolved in 60 ml of tetrahydrofuran (THF). To this were added 20 ml of 50% acetic acid aqueous solution and 2.0 g of zinc powder and reaction was allowed for two hours at 50° C. with stirring. Unreacted zinc was separated out by filtration, and the filtrate was concentrated. After addition of water to the residue, precipitated white crystals were collected by filtration. Recrystallized from THF/acetic acid/water gave 5.0 g of the aimed compound. mp. 271-273° C. TLC, Rf=0.89 (n-butanol/acetic acid/water=4/1/2).

Quelle