Dicyclohexylcarbodiimide → Boc-Asp(OtBu)-OSu

Participants

Reaction Steps

The resulting 11.45 g (39.7 mmoles) of oily BOC--Asp(OtBu)--OH and 4.6 g (40 mmoles) of N-hydroxy-succinimide are dissolved in 100 ml of dry dioxane. The solution is cooled until freezing, and then 8.25 g (40 mmoles) of DCC are added. The reaction mixture is stirred at room temperature overnight, the separated DCU is filtered off, and the filtrate is evaporated. The oily residue is solidified with a mixture of n-hexane and diisopropyl ether. The resulting crude product, weighing 13.8 and melting at 98°-102° C., is recrystallized from a threefold amount of isopropanol. 12.1 g (78.3%) of white, crystalline BOC--Asp (OtBu)--OSu are obtained; m.p.: 103°-105° C., [α]D : -25.6° (c: 1.0, in dioxane).

Provenance & Evidence