Réaction #1416

Équation de réaction

methyl iodide

Cesium carbonate

N2 [(1,1-dimethylethoxy)carbonyl]-N6 -[(phenylmethoxy)carbonyl]-L-lysine

water methanol

→

N2 [(1,1-Dimethylethoxy)carbonyl]-N6 -[(phenylmethoxy)carbonyl]-L-lysine, methyl ester

Solvants

—

hexanes

ethyl acetate

ethyl acetate

Conditions de réaction

Traitement

1. 1
   Autrethe residual water removed azeotropically with acetonitrile (3×)
2. 2
   AutreThe resulting oil was dried in vacuo
3. 3
   workup.DISSOLUTIONdissolved in dry dimethyl-formamide
4. 4
   Lavagewashed successively with water (2×25 ml.), saturated sodium bicarbonate (25 ml.) and brine (25 ml.)
5. 5
   SéchageThe organic phase was dried (anhydrous magnesium sulfate)
6. 6
   Filtrationfiltered
7. 7
   Autreevaporated to dryness
8. 8
   Autredried in vacuo
9. 9
   Autreto give 10.11 g

Mode opératoire

Cesium carbonate (4.28 g., 13.1 moles) was added to a mixture of N2 -[(1,1-dimethylethoxy)carbonyl]-N6 -[(phenylmethoxy)carbonyl]-L-lysine (10 g., 26.3 moles) and 20% water-methanol (60 ml.). The solution became homogeneous within 5 minutes so the solvent was stripped and the residual water removed azeotropically with acetonitrile (3×). The resulting oil was dried in vacuo, dissolved in dry dimethyl-formamide and treated with methyl iodide (3.2 ml., 2.0 eq.). The reaction mixture was stirred at room temperature for 1.5 hours under argon, diluted with ethyl acetate (200 ml.) and washed successively with water (2×25 ml.), saturated sodium bicarbonate (25 ml.) and brine (25 ml.). The organic phase was dried (anhydrous magnesium sulfate), filtered, evaporated to dryness and dried in vacuo to give 10.11 g., of product as a light yellow syrup; Rf =0.30 (ethyl acetate:hexanes, 1:2).

Source