Glycine methyl ester → Z-Trp-Gly-OCH3

Participants

Reaction Steps

To the suspension of 3.35 g (0.01 mol) of Z-Trp-OH and 1.25 g (0.01 mol) of H-Gly-OCH3 in 15 ml of dimethyl formamide there were added portionwise altogether 7 ml of water and subsequently 5.1 g of a finely powdered sodium bicarbonate. The suspension was largely clarified by adding dropwise 4 ml of methylethyl phosphinic acid anhydride. A sample of the reaction solution diluted with water showed a neutral reaction. Upon heating to room temperature the solution was stirred overnight and the solvents were separated by distillation in a high vacuum at room temperature. The residue was taken up in a mixture of 25 ml of water and 70 ml of ethyl acetate, the ethyl acetate extract was separated and the aqueous phase was extracted twice using each time 10 ml of ethyl acetate. The combined ethyl acetate extracts were washed twice using each time 7 ml of water, a 5% potassium bisulfate solution (until an acid reaction took place) and a saturated sodium bicarbonate solution (until s slightly alkaline reaction took place). Upon drying over magnesium sulfate the ethyl acetate solution was largely separated by distillation in vacuo and the residue was digested with diisopropyl ether.

Provenance & Evidence